Connecting mechanism for a motor vehicle locking system

Abstract

 A connecting mechanism for connecting a rotary shaft of a door locking system to a door latch is disclosed. It can be a problem that if this rotary shaft is removed, for example by a thief, by abuse or attack, it is a simple matter to actuate the latch to open the door of the motor vehicle without actuating an alarm system of the motor vehicle. The connecting mechanism of the present invention comprises a number of drive gears 20,34,40 disposed such that removal of a rotary shaft 28 from the mechanism causes the drive gears to become disengaged such that rotation of a first drive gear 20 will no longer cause a final drive gear 40 to be drive to actuate the door latch.

Description

[0001] The present invention relates to a motor vehicle assembly, and in particular to an improved connecting assembly for use in a motor vehicle lock system assembly.

[0002] It is a feature of some known lock systems to be fitted to a motor vehicle that they comprise a rotary shaft linking an exterior lock barrel to a side door latch. If this rotary shaft is removed, for example by a thief, by abuse or attack, it is a simple matter to actuate the lock drive of the latch to open the door of the motor vehicle without actuating an alarm system of the motor vehicle.

[0003] Some known systems overcome this difficulty by providing an additional shutter mechanism to the lock assembly. The additional shutter mechanism closes to prevent access to the lock drive if the shaft is removed. The provision of such an additional shutter mechanism adds to the cost and complexity of the lock assembly. Moreover, there are occasions when legitimate access to the lock assembly is required, for example during servicing of the motor vehicle lock assembly. Such servicing is made more difficult if the shutter mechanism is to be overcome in order to obtain access to the lock drive.

[0004] The present invention has as advantages that overcomes these difficulties. Further advantages of the present invention will be made clear below.

[0005] According to a first aspect of the present invention, a connecting mechanism for use with a motor vehicle locking system is characterised by a gear train having at least a first drive gear and a final drive gear, the first drive gear being adapted to retain a drive shaft, in which removal of the drive shaft from the first gear causes drive gears of the drive train to become axially displaced with respect to one another such that rotation of the first drive gear no longer causes the final drive gear to be driven.

[0006] Preferably, the first drive gear is adapted to be rotated about a first axis, to move between a first axial position and a second axial position on overcoming a first force, and further comprises a cam, the cam extending behind a second drive gear in a second radial position of the first drive gear, in that the second drive gear is adapted to be driven about a second axis by the first drive gear, the second drive gear being moveable between a first axial position and a second axial position on overcoming a second force, in that the final drive gear comprises a third drive gear adapted to be rotated about a third axis by the second drive gear when the second drive gear is in the first axial position, and in that if the first force is greater than the second force, the second drive gear is removed from driving engagement with the third drive gear.

[0007] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a plan view of a connecting mechanism according to the present invention for use with a motor vehicle locking system; and

Figure 2 shows a side view of the mechanism of Fig.1, the housing being shown in part section.

[0008] Referring to Figs. 1 and 2 there may be seen a connecting mechanism in accordance with the present invention. A housing comprising a base portion 2 and a cover portion 4 is provided. In the following, the cover portion 4 will be considered to be at a forward region of the connecting mechanism.

[0009] The base portion 2 is provided with a first spigot 6, a second spigot 8 and a third spigot 10. The first spigot 6 is provided within a recess 12 formed in the base portion 2. The second spigot 8 is provided to an edge of the recess 12. The second spigot 8 is provided with detent means 14. The cover portion 4 is provided with a boss 16. The boss 16 is of a suitable size and shape to receive a free end 18 of the second spigot 8.

[0010] A first drive gear 20 is provided, adapted to be rotatable about the first spigot 6. The first drive gear 20 includes a first gear wheel 22 having a plurality of drive teeth 24 disposed about at least a part of a periphery of the first gear wheel, engagement means 26 adapted to releasably engage a drive shaft 28, and a cam 30. In the illustrated embodiment, the cam 30 and the engagement means 26 are disposed on opposite sides of the first gear wheel 22.

[0011] The recess 12 in the base portion is adapted to receive the cam 30. The recess 12 defines a path through which the cam 30 may travel. Access to the engagement means 26 is provided through an opening 32 in the housing. The opening 32 may conveniently be provided between the base portion and the cover portion, or solely through the cover portion.

[0012] A second drive gear 34 is provided, adapted to be rotatable about the second spigot 8. The second drive gear 34 comprises a second gear wheel 36 having a plurality of drive teeth 38 disposed about at least a part of a periphery of the second gear wheel. The second gear wheel extends in a plane disposed forwardly of a plane through which the cam 30 of the first gear wheel is adapted to rotate.

[0013] In use, the second drive wheel 36 is normally located axially on the second spigot 8 by the detent means 14 on the second spigot, such that the plurality of teeth 24 of the first gear wheel mate with and drive the plurality of teeth 38 of the second gear wheel. A force F₂ is required to displace the second gear wheel 36 axially along the second spigot 8 beyond the detent means 14. The location of the boss 16 on the cover portion 4 prevents the second gear wheel 36 from becoming separated from the second spigot 8.

[0014] A third drive gear 40 is provided, adapted to be rotatable about the third spigot 10. The third drive gear 40 comprises a third gear wheel 42 having a plurality of drive teeth 44 disposed about at least a part of a periphery of the third gear wheel. In use, the third gear wheel 42 is located axially on the third spigot 10, such that the plurality of teeth 44 of the third gear wheel may normally mate with and be driven by the plurality of teeth 38 of the second gear wheel.

[0015] In the illustrated embodiment, the third drive gear 40 further comprises a first finger 46 and a second finger 48, teeth extending radially from the third drive gear.

[0016] In use, the components of the connecting mechanism are assembled as shown in Fig. 1 and Fig. 2 and the housing sealed. A drive shaft 28 from a lock system is inserted into the engagement means 26. A force F₁ is required to remove the drive shaft 28 from the engagement means 26.

[0017] The connecting mechanism is so constructed that the value of F₁ is greater than the value of F₂.

[0018] Under normal use, the drive shaft 28 is retained within and engages with the engagement means 26 of the first drive gear. Rotation of the drive shaft 28, caused by successful operation of the lock assembly causes rotation of the first gear wheel 22. This in turn causes the third gear wheel 42 to be driven by way of the second gear wheel 36. The radially extending first and second fingers 46,48 then act to operate a door latch mechanism.

[0019] If the drive shaft 28 is removed, for example by a thief while attempting to open the vehicle door, a force equal to or greater than F₁ must be exerted to remove the drive shaft 28 from the engagement means 26. In a locked position, the cam 30 is located behind the second gear wheel 36. Removing the drive shaft 28 thus causes the cam 30 to be brought into contact with the second gear wheel 36 with a force equal to or greater than F₁, that is a force greater than F₂, the force required to axially displace the second gear wheel 22 on the second spigot 8 beyond the detent means 14.

[0020] As a result removing the drive shaft 28 axially displaces the second gear wheel 36 on the second spigot 8. This removes the plurality of teeth 38 about the periphery of the second gear wheel from mating with the plurality of teeth 44 about the periphery of the third gear wheel, thereby disengaging the second gear wheel 36 from the third gear wheel 42.

[0021] When the second gear wheel 36 has been displaced, the first gear wheel 22 may or may not be able to drive the second gear wheel 36. In either case, the second gear wheel 36 cannot be made to drive the third gear wheel 42 while the second gear wheel 36 is in the axially displaced position. This is true independent of the force applied to the first ger wheel 22 applied through the opening 32.

[0022] When the drive shaft 28 is to be removed for a legitimate reason, for example during repair or servicing, the lock system is first moved to an unlocked position. When the lock system is in the unlocked position, the cam 30 is driven by the drive shaft 28 to take up a position in which the cam 30 extends to one side of the second gear wheel 36 and not behind the second gear wheel 36. Thus when the drive shaft 28 is removed, the cam 30 is axially displaced alongside the second gear wheel 36 and does not axially displace the second gear wheel 36. The first gear wheel 22 can then be returned to its original axial position, for example by reassembling the drive shaft 28 into the engagement means 26.

[0023] Should the second gear wheel 36 be displaced axially, either by an attempted break-in or by a mistake during repair or service, the second gear wheel 36 may be returned to the correct axial position by use of a tool through a special access hole 50 provided in the cover portion 4 or by removal of a part of the cover portion.

Claims

1. A connecting mechanism for use with a motor vehicle locking system characterised by a gear train (20,34,40) having at least a first drive gear (20) and a final drive gear (40), the first drive gear (20) being adapted to retain a drive shaft in which removal of the drive shaft (28) from the first gear (20) causes drive gears of the drive train (20,34,40) to become axially displaced with respect to one another such that rotation of the first drive gear (20) no longer causes the final drive gear (40) to be driven.

2. A connecting mechanism according to claim 1, characterised in that the first drive gear (20) is adapted to be rotated about a first axis, to move between a first axial position and a second axial position on overcoming a first force, and further comprises a cam (30), the cam (30) extending behind a second drive gear (34) in a second radial position of the first drive gear (20) in that the second drive gear (34) is adapted to be driven about a second axis by the first drive gear (20), the second drive gear (34) being moveable between a first axial position and a second axial position on overcoming a second force, in that the final drive gear (40) comprises a third drive gear (40) adapted to be rotated about a third axis by the second drive gear (34) when the second drive gear (34) is in the first axial position, and in that if the first force is greater than the second force, the second drive gear (34) is removed from driving engagement with the third drive gear (40).

3. A mechanism according to claim 2, characterised in that the drive shaft (28) is retained in the first drive gear (20) by a force greater than the first force.

4. A mechanism according to claim 2 or claim 3, characterised in that the third drive gear (40) further comprises a first radially extending finger (46) and a second radially extending finger (48).

5. A mechanism according to any of claims 2 to 4, characterised in that the first axis comprises a first spigot (6).

6. A mechanism according to any of claims 2 to 5, characterised in that the second axis comprises a second spigot (8).

7. A mechanism according to any of claims 2 to 6, characterised in that the third axis comprises a third spigot (10).

8. A mechanism according to any of claims 2 to 7, characterised in that the mechanism further comprises a housing (2,4) in which the first, second and third spigots (6,8,10) are integrally formed.

9. A mechanism according to claim 8, characterised in that a boss (16) is provided in the housing (2,4) to receive a free end (18) of the second spigot (8).

10. A mechanism according to claim 8 or 9, characterised in that an access hole (50) is provided in the housing (2,4) to allow the second drive gear (34) to be axially displaced.

11. A motor vehicle locking system characterised in that it incorporates a connecting mechanism according to any one of the preceding claims.

Drawing