GB2350146A

GB2350146A - Motor vehicle lock assembly

Info

Publication number: GB2350146A
Application number: GB9910983A
Authority: GB
Inventors: Simon Andrew Whorlow
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1999-05-13
Filing date: 1999-05-13
Publication date: 2000-11-22
Also published as: EP1052351A2; EP1052351A3; GB9910983D0

Abstract

Locks are known comprising a locking cylinder, a sleeve and a housing. The sleeve 8 is freely rotatable in the housing 4. The cylinder 6 includes a number of locking plate. When a correct key has been inserted, the locking plates are retained within the cylinder and the cylinder will rotate relative to the sleeve and housing to release a latch. When an incorrect key has been inserted, at least one of the plates extends into the sleeve to drive the sleeve at 34 relative to the housing. The presence of camming surfaces 38',40' will cause the sleeve or means carried by and driven by the sleeve to be displaced axially with respect to the housing causing the latch mechanism to be isolated from the cylinder. However, should a part of the cylinder break, the latch mechanism may no longer be isolated from the latch when an incorrect key is inserted. An improved sleeve assembly 8' is disclosed in which such breakage of the shaft is accommodated such that even if the shaft becomes broken the cylinder and the latch are declutched from one another. The assembly 8' is formed in two parts 60,62 respectively engaged by the locking plates and formed with cam surfaces and interengaging at 64,66 to allow relative axial movement.

Description

2350146 Motor Vehicle AssemWy The present invention relates to an improved

cylinder lock, and in particular, but not exclusively to a cylinder lock for use in motor vehicles.

It is known to incorporate a declutch function into the operation of some kinds of cylinder lock. Such a function permits the rotation of a key in the lock; however only in the case of a correct key will the rotation of the key be converted to movement of a latch mechanism connected to the cylinder lock.

One such lock comprises a locking cylinder, a sleeve and a housing. The sleeve is freely rotatable in the housing. The cylinder includes a number of locking plates. When a correct key has been inserted, the locking plates are retained within the cylinder and the cylinder will rotate relative to the sleeve and housing to release a latch. When an incorrect key has been inserted, at least one of the plates extends into the sleeve to drive the sleeve relative to the housing. The presence of camming surfaces will cause the sleeve or means carried by and driven by the sleeve to be displaced axially with respect to the housing. Axial movement of the sleeve causes the latch mechanism to be isolated from the cylinder, and so rotation of the cylinder by the incorrect key no longer causes actuation of the latch mechanism.

However, should a part of the cylinder break, the latch mechanism may no longer be isolated from the latch when an incorrect key is inserted. Once such a break has occur inserting any key into the keyway that results in rotating of the cylinder will cause the latch to be actuated. It is clear that such a defect has adverse security implications for a vehicle fitted with such a declutch mechanism.

It is an aim of the present invention to eliminate, or at least substantially reduce, this problem.

According to a first aspect of the present invention, a cylinder lock sleeve comprises a first body portion and a second capping portion, the first body portion including drive surfaces and keying means, the second capping portion including keying means for mating with the keying means of the first body portion and camming surfaces According to a second aspect of the invention, a cylinder lock incorporates a cylinder lock sleeve according to the first aspect of the present invention.

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which; Figure 1 shows a prior art mechanism in side section;

Figure 2 shows a side view of a cylinder and first and second cap elements of the lock mechanism in section; Figure 3 shows a side view of a sleeve and the first cap element of the lock mechanism; Figure 4 shows a side view of a cylinder lock sleeve according to the present invention; and Figure 5 shows a side view of the cylinder lock sleeve of Figure 4 with the components of the sleeve slightly displaced from one another.

Referring first to Figures I to 3, there may be seen an embodiment of a lock assembly 2 according to the prior art. The lock assembly 2 comprises a housing 4, a lock cylinder 6, a sleeve 8, a first cap element 10, a second cap element 12, a generally "U"-shaped plate 14, spring means 16 and a latching finger 18. The lock cylinder 6 has a body part 20 and a shaft 22 extending from the body part. The body part 20 includes a keyway 24 and passageways 26 offset from the keyway in which are housed tumbler plates 28. The shaft 22, which rotates with the body 20 when the body is driven by a key (not shown), includes detent means 30 extending radially from the shaft and a groove 32 spaced from a remote end, of the shaft. The plate member 14 engages with the slot and is held in place by the spring means 16 urging apart the plate and the second cap element 12. The detent means 30 conveniently comprises radially extending lugs.

The sleeve 8 is located within the housing 4 and is free to rotate within the housing. The sleeve 8 includes drive surfaces 34 which may be engaged by any tumbler plate 28 extending beyond a periphery of the cylinder 6. The drive surfaces 34 may be formed by individual passageways in the sleeve to accommodate individual tumbler plates (as shown in Figure 3), or by a common passageway in the sleeve to accommodate a number of turabler plates (as shown in Figure 1). The sleeve 8 ftirther includes camming surfaces 38 at an end remote from a keyway entry point of the lock. The cylinder 6 is located within the sleeve 8, and in the absence of any tumbler plates extending beyond the periphery of the cylinder, for example when a correct key is inserted, the cylinder 6 is free to rotate within the sleeve 8. The inner surface of the sleeve includes a surface 40 which rests on a first surface 42 of the cylinder to maintain the sleeve axially with respect to the cylinder body.

The first cap element 10 has mating camming surfaces 44 to those of the sleeve and rests on and is driven by the sleeve 8. The first cap element 10 is mounted within the lock housing 2 such that rotation of the first capping element is prevented. This may conveniently be achieved by the use of a ridge 46 formed on the first cap element 10 being retained within an axially extending groove 48 provided in the housing 2. The first cap element further includes an interior seating surface 50 on which the second cap element 12 may be seated.

The second cap element 12 is seated within the first cap element on the seating surface and has detent means 52 that rest upon and are driven by the cylinder detent means 30.

The second cap element 12 includes axially extending fingers 54 which are seated within a recess provided on the plate 14. Rotation of the second element 12 will drive the plate 14.

The latch finger 18 is retained over a remote end of the cylinder shaft 22 by the plate 14, such that rotation of the plate 14 causes rotation of the latch finger 18. Rotation of the latch finger 18 causes actuation of a latch mechanism (not shown).

Thus, if the sleeve 8 is driven, for example by the insertion of an incorrect key, the first capping element 10 is driven by the mating camming surfaces 38,44 axially within the housing 2 away from the keyway entry point. This in turn moves the second cap element 12 away from and off the cylinder detent means 30. Rotation of the cylinder is no longer able to cause rotation of the second cap element 12 which in turn means that the latch finger 18 cannot be rotated.

However, should the cylinder 6 become broken, for example by a crack extending across the tumbler plate passageway furthest from the keyway entry point, at least one of the detent means 30 on the cylinder is moved from its intended position. In particular the relative axial displacement of the detent means 30,52 and the camming surfaces 38, 44 means that axial movement of the first cap element 10 along the housing no longer moves the second cap element 12 from off that detent means which is out of position. In such an instance, insertion of an incorrect key will cause the sleeve 8 to be driven, the camming surfaces 38,44 to drive the first cap element 10 and the carried second cap element 12 axially as before, however rotation of the cylinder 6 will still cause the second cap element 12 to be driven, thereby causing rotation of the latching finger 18.

It is an object of the present invention to prevent this from happening. This may be achieved by the use of a two part sleeve element as illustrated in Figures 4 and 5. The sleeve element 8' comprises a main body portion 60 and a capping element 62. The main body portion 60 includes the driving surfaces 34' for the tumbler plates and channel means 64 to receive finger means 66 of the capping element 62. The capping element includes finger means to be received in the channel means of the main body portion and camming surfaces 38'. The capping element 62 is able to move axially with respect to the main body portion 60. The capping element 62 includes a surface 40' which rests upon a first surface of the cylinder (not shown) to maintain the capping element 62 in position axially with respect to the cylinder surface (not shown).

When the sleeve element 8' is assembled it has the form of the sleeve element 8 as 5 described above. However, due to its two part nature it performs differently.

The remainder of the lock assembly is as described above.

When the cylinder is intact, the operation of the lock is as described above. However, when the cylinder is broken by a crack such that at least one of the detent means are deformed out of position axially, the capping element 62 carrying the camming surfaces 38' is carried axially by the deformed cylinder at least by an amount corresponding to an axial thickness of the crack along the lock housing, i.e. the amount by which the cylinder surface 40 has been axially displaced. In this way the camming surface 38' against which the camming surface 44 of the first cap element 10 acts is axially displaced by at least an amount corresponding to the movement of the first surface of the cylinder. This in turn ensures that the detent means of the second cap element are carried axially beyond the location of the cylinder detent means which have been deformed out of position. In this case, rotation of the sleeve 8' causes the first cap element 10 to be driven such that it carries the detent means 52 of the second cap element away from the cylinder detent means 30. Accordingly rotation of the sleeve 8' when the cylinder 6 is broken as described will no longer cause rotation of the latching finger 18.

It will be understood that the capping element may be displaced a further axial distance away from the keyway entry. In such an instance, the detent means of the second cap element are carried axially further beyond the location of the cylinder detent means which have been deformed out of position, and as such rotation of the sleeve will no longer cause rotation of the latching finger.

1

Claims

-6CLAIMS

1. A sleeve for a lock assembly, the sleeve comprising a first body portion and a second capping portion, the first body portion including drive surfaces and keying means, the second capping portion including keying means for mating with the keying means of the first body portion and camming surfaces.

2. A sleeve according to claim 1, characterised in that the first body portion keying means comprises at least one channel in an outer surface of the first body portion and in that the second capping portion keying means comprises ai least one axially extending member which is adapted to be received within the at least one channel.

3. A sleeve substantially as described herein with reference to and as illustrated with reference to Figures 4 and 5 of the accompanying drawings.

4. A lock assembly characterised in that the lock assembly includes a sleeve according to any of claims 1 to 3.

5. A lock assembly according to claim 4, in which the lock assembly further comprises a lock housing, a cylinder lock comprising a body portion for location within the sleeve, and a shaft extending beyond the body portion into the lock housing, the body portion including a plurality of tumbler plates and the shaft including detent means, a first capping element comprising camming surfaces for mating with the camming surfaces of the sleeve and means for preventing rotation of the first capping element in the lock housing, a second capping element adapted to be carried by and rotatable with respect to the first capping element and comprising detent means adapted for engagement with the cylinder detent means and axially extending members, a latching finger, a locking plate for engagement with the cylinder shaft thereby to retain the latching finger on the cylinder shaft, the locking plate including means to mate with the axially extending members of the second capping element, and spring means located between the second capping member and the locking plate.

6 A lock assembly according to claim 5, characterised in that the camming surfaces of the sleeve extend axially into the camming surfaces of the first capping element.

7. A lock assembly according to claim 5 or claim 6, characterised in that the detent surface of the cylinder comprises at least one radially extending lug.

8. A lock assembly according to any of claims 5 to 7, characterised in that means to mate the locking plate with the axially extending members of the second capping element comprises a recess in the locking plate.

9. A lock assembly incorporating a sleeve substantially as described herein with reference to and as illustrated with reference to Figures 4 and 5 of the accompanying drawings.

A lock comprising a cylinder and a sleeve for location about the cylinder, the cylinder incorporating detent means including a surface, and the sleeve having a surface characterised in that the axial spacing between the sleeve surface and the detent surface is maintained when the detent means is deformed out of position.