This invention concerns anti-theft devices for loc ing onto a car steering wheel to prevent or limit the movement of the steering wheel.

Vehicle anti-theft devices in the form of steering wheel immobiliser bars are well-known, and the present invention is a development of one such device, which is the subject of our earlier UK Patent No. 2,246.990.

UK Patent-No. 2.246,990 discloses an anti-theft device, which comprises an immobiliser bar and a locking arrangement mounted at one end of the bar for locking the bar onto a steering wheel. According to this patent, the locking arrangement fastens onto one side of the rim of the steering wheel in use. and the immobiliser bar is arranged to extend over the hub of the steering wheel and to pass through and behind a portion of the steering wheel rim on the opposite side from that engaged by the locking arrangement. The locking arrangement comprises a base part attached to the immobiliser bar, a hinged cover pivotably mounted on the base part so as to be engageable around the rim of the steering wheel, and a spring-loaded latching arrangement for locking the cover in a closed position on the rim.

The design disclosed in our earlier patent has advantages in terms of the way in which the immobiliser bar engages the steering wheel because the bar is both difficult to remove and suits a wide variety of steering wheel designs. However, a more secure form of locking arrangement is considered desirable to meet current British standards.

Another form of anti-theft device is disclosed in US Patent No. 5.024,069 and comprises an immobiliser bar having a pair of hook members rigidly fixed to the bar. A locking assembly is rotatable around the bar to and from a position in which it closes the entrances to the two hook members. In this position, when the hook members are engaged over the rim of a steering wheel, the locking assembly can be locked relative to

the bar and the hook members in order to secure the bar and so that it projects tangentially from the steering wheel.

A disadvantage of the arrangement of this US patent is that the locking arrangement is cumbersome. Further, the immobiliser bar is engaged with the steering wheel only by the hook members and not by the bar itself so that security of attachment is reduced and some limited movement of the steering wheel still remains possible even when the anti- theft device is attached to the wheel.

It is an-object of the present invention to produce an anti-theft device of the kind disclosed in UK Patent No. 2,246.990 but having an improved locking arrangement.

A further object of the present invention at least in its preferred form is to provide an anti-theft device which is versatile and suitable for use in a wide variety of vehicles and which has a secure and rigid locking arrangement for mounting the device on a steering wheel.

According to the present invention, there is provided an anti-theft device for a motor vehicle comprising an immobiliser bar for fitting across a vehicle steering wheel so as to project :nerally radially from the steering wheel to prevent or limit rotation thereof by contact with other parts of the vehicle, and a locking arrangement mounted at one end of the immobiliser bar for locking the immobiliser bar onto the rim of the steering wheel at one side thereof, the locking arrangement comprising a pair of hooks pivotably connected to the immobiliser bar for movement around an axis perpendicular to the immobiliser bar between an open position in which the free ends of the hooks are remote from the bar for engaging over the steering wheel rim and a closed position in which the free ends of the hooks extend past the immobiliser bar for securing the immobiliser bar into the steering wheel rim. and a locking assembly for rigidly securing the hooks in the closed position.

In a preferred embodiment of the invention, the pair of hooks are formed by two prongs of a unitary fork element.

Preferably also, the unitary fork element is pivotably connected to the immobiliser bar by means of a sleeve rigidly attached to one end of the bar immobiliser.

Advaniageousiy, the locking assembly includes means for rigidly engaging free ends of the hooks.

For example, the locking assembly may comprise first and second locking pin assemblies, each for engaging a notch in a respective one of the free ends and each comprising a lock pin engageable with the associated notch, a lock element moveabie axially relative to the lock pin and resiliently biased in a direction away from the lock pin, and a cam lock arranged to engage the lock element and force it against the lock pin so as to rigidly engage the lock pin with the associated notch.

In the embodiment described below, the lock pin constitutes a closed outer sleeve, and the lock element constitutes an inner pin slidable within the outer sleeve.

The invention is described further, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of an anti-theft device according to the present invention;

Figure 2 is a perspective view of the anti-theft device with parts broken away to show a locking arrangement of the device;

Figure 3 is a side view, partially in section, of a hook of the locking arrangement and its mounting relative to an immobiliser bar of the device;

Figure 4 is an axial view along the immobiliser bar partly in section, showing details of a locking assembly of the locking arrangement; and

Figure 5 is a section through a portion of the locking assembly, showing in Figure 5a the locking assembly in a latched position and showing in Figure 5b the locking assembly in a deadlock position.

Referring to the drawings, an anti-theft device according to the present invention comprises an immobiliser bar 10 and a locking arrangement 12 mounted at one end of the immobiliser bar 10. The immobiliser bar 10 has a curved and slightly S-shaped configuration so that when the locking arrangement 12 is secured to die rim of a steering wheel at one side thereof the immobiliser bar 10 extends across the hub of the steering wheel and then through the steering wheel to engage behind the rim at the opposite side thereof. These features are described in our UK Patent No. 2,246,990. In this position, the free end of the immobiliser bar 10 projects generally radially beyond the steering wheel in use and prevents or limits rotation of the steering wheel by contaα with other parts of the vehicle.

As shown in Figures 1 and 2, the locking arrangement 12 comprises a unitary fork element 14 having a pair of hooked prongs 16 joined by a cross bar 18. The fork element 14 is made from substantial spring steel so that it cannot readily be severed by thieves. The fork element 14 is mounted relative to the immobiliser bar 10 so that it can pivot about an axis which lies perpendicular to the longitudinal axis of the immobiliser bar 10. In other words, the hooks 16 are pivotable about an axis which coincides with the axis of the cross bar 18. Such mounting of the fork element 14 is achieved by means of a U-shaped member 20, shown in Figure 3, formed from hardened mild steel and slotted over the end of the immobiliser bar 10 and bolted onto die bar 10 by means of a bolt 22. The U-shaped member 20 is formed with a sleeve 24 which receives me cross bar 18 of the fork element 14 in a snug fitting relationship. Consequently, the fork element 14 is pivotable between an open position in which free ends 26 of d e hooks 16 are located remote from the immobiliser bar 10 and a closed position in which the free ends 26 of the hooks 16 extend past the immobiliser bar 10. Both positions are shown in Figures I and 2 and the closed position is shown in Figure 3.

In the open position of the fork element 14, the immobiliser bar 10 can be fitted through a vehicle steering wheel so that its two ends engage opposite faces of the steering wheel rim on opposite sides of the steering wheel hub. In this condition, the hooks 16 very loosely engage the steering wheel. By then moving the fork element 14 into the closed

position, the hooks 16 are firmiy engaged with the steering wheel rim to fix the immobiliser bar to the steering wheel.

A locking assembly 30. shown in Figures 2, 4 and 5, is included in the locking arrangement 12 for rigidly securing the fork element 14 in the closed position. As shown, the locking assembly 30 comprises first and second locking members 32, each of which is engageable within a respective notch 34 provided in die free end 26 of an associated one of the hooks 16. The two locking members are controlled by a cam lock 36. Only one of die locking members will be described.

Referring principally to Figures 5a and 5b, the respective locking member 32 comprises a lock pin 38 having a rounded tip 40 of complementary shape to the associated notch 34 and having also a female opening 42. The locking member 32 further comprises a male lock element 44 received within the female opening 42. The male lock element 44 has a head 46, and a spring 47 is provided between the head 46 and the interior of the lock pin 38 to bias d e two apart. The locking member 32 is guided within a bore 48 in a housing 50 so that the rounded tip 40 of die lock pin 38 projects laterally beyond die housing 50.

The fork element 14 is designed so Uiat the two hooks 16 in die closed position sit on either side of the housing 50 and, as each hook 16 is moved into d e closed position, it slides past the lock pin 38 depressing it against die force of the spring 47 until die notch 34 is aligned with the lock pin 38. Then, die rounded tip 40 springs into die notch 34 to hold the hook 16 in this position. This is the latched position of the locking member 32 and it is shown in detail in Figure 5a.

The cam lock 36 is rotatably mounted in the housing 50 so ϋiat a cam member 52 of the cam lock 36 projects into the bore 48 behind die head 46 of the locking member 32. In the latched position shown in Figure 5a, the cam member 52 does not bear against die head 46.

However, when d e cam lock 36 is turned, die cam member 52 gradually and increasingly bears against die head 46 to urge d e male lock element 44 right into the female opening 42 of die lock pin 38. The head 46 is dius forced against die end of die lock pin 38 and die two parts of the locking member 32 rigidly engage one anodier to fix the rounded tip 40 in the notch 34. This is d e deadlock position shown in Figure Sb and in this position no movement of parts of the locking member 32 relative to one anodier or of the locking member 32 relative to the notch 34 is possible. Consequently, the hook 16 is rigidly secured in the closed position. Release of die fork element 14 is only possible by operation of die cam lock 36 followed subsequently by snapping the locking member 32 out of d e notch 34.

The immobiliser bar 10 shown in Figures 1 to 3 is encased within a polyurethane foam cover 60. This cover stops just short of die housing SO and die bar 10 is attached to die housing 50 by means of rivets (not shown). The seating of the bar 10 without its cover in die housing 50 is shown in section in Figures Sa and Sb.

The present invention has die advantage of providing a robust and easy to operate anti- theft device. For added security, the two hooks 16 can be engaged with the steering wheel rim on eidier side of a radial spoke of die steering wheel to provide a tamper-proof arrangement in which disengagement of the immobiliser bar 10 from the steering wheel by unnatural means would require severing of d e steering wheel rim or of the hooks 16 in more than one position.