The present invention relates to a lock primarily intend for motor vehicles but which may be used for oth purposes.

Motor vehicle locks commonly comprise a barrel type lock which the key when inserted is turned to switch on vehic services then to actuate the starter motor. It is comm to include a steering column lock to prevent the steeri wheel from being turned when the key has been removed fr the lock. Many of these locks have, however, only limit security in that they can be picked, forced, shimme drilled or extracted without great expertis Consequently, there has been a tendency to fit alarms t vehicles. These, however, are increasingly ignored and ca themselves be circumvented.

An improved lock is shown in my US Patent No. 1,794,796 however, this has certain disadvantages in that it is to easy to disable or "upset".

It is an object of the present invention to provide a improved lock suitable for a motor vehicle.

A lock according to the invention comprises a housing, key receiving barrel mounted in the housing, the barre capable of axial movement relative to the housing, means t constrain the axial movement of the barrel, sai constraining ' means comprising an electrically operabl solenoid arranged to be actuated by an initiating signal.

An advantage of the lock according to the invention is that if the barrel is unconstrained any attempt to force the lock will cause the barrel to move axially to an upset position such that rotation of the barrel cannot unlock the lock. A further advantage of this arrangement is that when a correct key is in the lock and it is desired to quickly disable the lock in the event of a highjack, it is only necessary to punch the key to upset the lock.

In a preferred embodiment of the invention the lock is arranged to actuate an electrical switch to provide electrical supplies to a vehicle and may also actuate a starter motor. The lock may also be adapted to move a bolt into and out of a steering column.

In the embodiment where the initiating signal is derived from an infrared receiver within the housing, a sensor is mounted to a front face of the lock housing. The receiver circuitry is housed within the housing. If a correct infrared signal is received by the receiver the solenoid will be actuated to prevent axial movement of the lock barrel. This enables a correct key to be inserted in the lock barrel without upsetting the lock. The key can then be turned to remove a steering wheel lock where this is fitted. The key can be then further turned to actuate an electrical switch and to start a vehicle engine.

If no correct signal is received by the receiver there will be no constraint on the axial movement and any attempt to insert a key even though a correct key, will upset the lock so that control of devices operated by the lock will not be possible since the lock barrel will freely rotate.

Whilst an infrared receiver is one way of actuating the solenoid an alternative embodiment employs a magnetic card

WO 93/13967 PCT/GB93/00042

- 3 -

or strip reader mounted in the lock housing.

An embodiment of the invention will now be described with reference to the accompanying drawings in which:-

Figure 1 is a front elevation of a lock according to 5 the invention,

Figure la is a horizontal cross section taken on I-I of Fig. 1,

Figure 2 is a vertical cross section taken on II-II of Fig. 1, 10 Figure 2a is a horizontal cross section taken on X of

Fig. 2 as seen from below,

Figure 3 is a vertical cross section taken on III-III of Fig. 2,

Figure 4 is a vertical cross section taken on IV-IV of 15 Fig. 2,

Figure 5 is a vertical cross section taken on V-V of Fig. 2 ,

Figure 6a is an end elevation of cam assembly 24 as seen from X shown in Fig. 2a, 20 Figure 6b is a side view of the cam assembly shown in

Fig. 6a,

Figure 6c is an end elevation seen from Z of an operating block 20 shown in Fig. 2a,

Figure 6d is a vertical cross section taken on VI-VI 25 of Fig. 6c,

Figure 6e is a plan view of the block of Fig. 6c, Figure 7 is a vertical end view of a barrel 2 with a key stop member seen from Y in Fig. 2a,

Figure 7a is a partial side view of the end of the 30 barrel and key stop member of Fig. 7 seen from A in Fig. 7, Figure 8 is a vertical end view of the stop member for the barrel end of Fig. 7,

Figure 8a is a side view of the key stop member of Fig. 8 as seen in Fig 8 from A. 35 Figure 9 is a circuit block diagram of an infrared

transmitter according to one embodiment of the invention for enabling the lock of Figure 1 to 8a.

Figure 10 is a circuit block diagram of an infrared receiver for receiving the enabling transmission of the transmitter of Fig. 9, and

Figure 11 is a circuit block diagram of a magnetic strip readout receiver according to a second embodiment of the invention for enabling the lock of Figures 1 to 8a.

Referring to the drawings, the lock shown is adapted to be fitted to a steering ^' column (not shown) of a motor vehicle.

As shown in Figure 2 the lock comprises mainly cylindrical housing 1 in which a key slot 51 (see Fig. 1) is axially provided on axis X. The cylindrical part of the housing contains a lock barrel 2 with an axially extending round portion 2a terminating with a double D section 2b (the double D section being shown at 52 in Fig. 2) . Below the cylindrical part of housing 1 is a radially extending portion 53 housing a steering shaft lock bolt 21 and a parallel radially extending portion 54 housing a solenoid 14 for locking barrel 2. The portion 53 extends to a bracket portion 55 arranged to receive bolts (not shown) in bolt holes 56 (see Fig. la) . The bolts secure the lock to the steering column tube (not shown) . The lock barrel 2 also has at its outer key entry end a key stop portion 2c at the key entry which houses a plate 3 which is enabled to slide in a direction B (shown in Fig. 2a and 7a) . Details of the portion 2c and plate 3 are shown in Fig.s 7 to 8a.

The barrel 2 is rotatably mounted in a sleeve 4 and secured axially thereto by a circlip 4a (see Fig. 2a) . Surrounding the outer part of the barrel 2 is a hardened steel liner 5 to protect the barrel.

The sleeve 4 with barrel 2 is shown in Fig. 2 in the lock operative position but is movable axially in chamber 57 to the rear to an upset position, cavity 6 in block 7 allowing key 12 extending from sleeve 4 to rotate in the upset position.

Behind block 7 is a fixed block 8 to provide support to plunger 9. Plunger 9 is normally pressed by compression spring 10 onto sleeve 4, spring 10 acting between the plunger 9 and solenoid armature 15. Armature 15 is normally pressed outwards away from sleeve 4 by means of compression spring 11. Sufficient pressure is provided by spring 10 to ensure plunger 9 provides a slight drag on sleeve 4. After actuation of solenoid 14 spring 11 resets armature 15.

In order to prevent rotation of sleeve 4 in the lock operative position a keyway 13 (see Fig. 5) is provided in block 7 which guides key 12 extending from sleeve 4. Key 12 is released from keyway 13 as indicated above on key 12 moving rearwardly to coincide with cavity 6.

A further block 16 (see Fig.s 2 and 4) is provided to the rear of block 8. Block 16 has a groove way 17 into which plunger 18 can be pressed by spring 19. Plunger 18 acting in way 17 prevents barrel 2 and sleeve 4 from being pulled forward. That is plunger 18 retains the barrel in the rearward or upset condition.

To the rear of block 16 is a spacer 58 beyond which is an operating block 20 (see Fig.s 2, 6c-e) which can move radially under pressure of spring 23. Block 20 is arranged to act on bolt 21 and to retract bolt 21. A further spring 22 acts between bolt 21 and block 20.

Figures 6a and 6b show a cam assembly 24 held in position by circlip 26 to plate 25 mounted to the rear of block 20.

A track 24a designed to give a positive lift to block 20 engages with a lug 24b extending from assembly 24. Lug 24b engages with and 20a in block 20 (see Fig. 6c) when the key ^'' is turned towards the engine start position. Spring 23 acts on the block to rotate spindle portion 2a to the engine running position.

A further circlip 27 secures plate 25 in the housing to the rear of assembly 24 a dog member 28 engages assembly 24 and is movable rearwardly by face 60 at the rear end of extension 2a. A compression spring 29 maintains dog 28 and assembly 24 in contact through plate 25 and also serves to maintain movable contact plate 30 and fixed contacts 31 in operable association.

An insulating sleeve 32 which carries spring 29 prevents spring 29 from obstructing movement of dog 28.

An electrically insulating block 33 held between ridge 61 of contact housing 36 and circlip 35 provides a mounting for fixed contacts 31. Block 33 (see Fig.s 2 and 3) has a membrane 34 which maintains the working pressure needed for the contacts and also prevents upset of the lock in the engine running condition. However, membrane 34 is also designed to shatter at a predetermined loading occasioned by impact on barrel 2 and extension 2a and 2b. This shattering of the membrane can be used to disable the switch in the event of highjack or else can be used in a crash to disable the switch.

Contact housing 36 is held to main housing 1 by circlip 37. An insulated block 38 providing an abutment for spring 29

is held to extension 2b by circlip 39.

A lever 40 (see Fig. 2a) in the forward part of housing 1 acts to obstruct operating block 20 from locking the steering.until the key is removed from barrel 2. The outer end 40' of lever 40 rides on plate 3 and lies between 2c and 2d depending on whether the barrel 2 is in the forward operative position shown in Fig. 2a or in the. rearward upset position.

A trip pawl 41 is in operating block 29 under influence of spring 42 (see Fig. 2a) .

A spring 43 ensures lever 40 remains clear of pawl 41 in locked condition.

A microswitch 44 below lever 40 indicates that the key is left in barrel 2 if vehicle door is opened.

A cavity 46 in the main housing 1 is provided for an amplifier and decoder for infrared sensor 45. The amplifier applies an initiating signal received by sensor 45 to operate solenoid 14. In a second embodiment cavity 46 contains a magnetic strip readout receiver, the strip being inserted through a slot shown in broken line at 45' in Fig. 1 replacing sensor 45. The circuit for the magnetic strip readout is inserted as shown in Fig. 11 at 64. The circuit for switch 62' operates as switch 62 below.

In order to insert the key it is necessary to transmit a coded infrared signal from a customised fob unit comprising a conventional infrared signal transmitter 60 shown in Fig. 9 but which is not described in detail because it is a well known proprietary item.

The infrared signal is received by sensor 45 mounted in the front face of the lock housing 1 and is amplified and decoded by an integrated receiver unit 61 (see Fig. 10) all housed within cavity 46. If the signal is correct the solenoid 14 within the housing will actuate and prevent axial movement of the lock barrel 2 and allow insertion of the correct key whereby release of steering and start up of the engine can be achieved in a normal manner. As soon as the ignition switch is turned on, switch 62 which is part of the ignition switch opens and disables the receiver.

A predetermined time delay in the enabling circuit of the receiver unit ensures that if the key is not operated within the predetermined time, the solenoid will release the constraint on the key barrel.

It will be appreciated that the solenoid 14 when actuated acts on plunger 9 to apply more pressure on sleeve 4 to prevent rearward movement of the sleeve. In the absence of this additional pressure key insertion causes the sleeve to move rearwardly to the upset position where dog 28 is disengaged from cam 24 which in turn prevents lifting of block 20.

It will also be appreciated that on insertion of a key into key slot 51 the plate 3 causes lever 40 to tilt about pivot 70 (see Fig. 2a) . The rear end of 40" then moves over the top slope 41' of pawl 41 as shown in a broken line in Fig 6d. As the key is turned and block 20 is lifted pawl 41 retracts as block 20 lifts. Conversely when the key is turned to OFF end 40" prevents block 20 from returning to the locked position by the means of pawl 41 engaging on the top end 40" when the key is removed lever 40 tilts back removing end 40" from the pawl 41. The block under the pressure of spring 23 causes the bolt 21 to enter the

steering column.

If no correct signal is received or if the power supply t the switch is broken there will be no constraint on th axial movement of the barrel and in an attempt to insert key or use force in any form the lock assembly will move t the upset condition when control of the components i disengaged. Likewise the electrical contacts 30, 31, 30' and 31' are broken and the portion of the apparatu associated therewith rotates freely.

If the lock has been upset ^• it can only be reset with th correct key by inserting and giving a flick in a clockwise direction then continuing to turn, while at the same time pulling outward on the key the control sleeve 4 of the lock barrel housing will be felt to enter its stop position which in this case the key is in the engine start position. At this point the steering is locked but the engine cannot start because the contacts are held off by membrane 34 obstructing the dog 28 which engages with the lifting cam assembly 24. Still pulling on the key turn to "OFF" when all associated components will align with the key way 13 and the lock is ready for normal operation. This membrane 34 will also prevent the lock from going into the upset state when in the run position due to say lumpy road conditions. This feature will also act as an inertia switch cutting the engine in the event of a frontal impact thus eliminating the risk of fire.

Once the key has been turned to the run position the arrangement of the apparatus is such that on turning to

"OFF" the steering remains unlocked until the key is extracted. If the vehicle door is opened and the key is still inserted an audible alarm will be activated by microswitch 44.

It can also be arranged that an alarm can be activated should the device be put into the upset condition.

This arrangement of the apparatus is such that an incongruous or undesirable situation cannot arise in that it should be impossible to have the steering locked and the engine on or the key withdrawn unless the steering is locked.

In a preferred embodiment any two barrel levers should have the external widths made small to prevent the picking of the lock by holding against the housing. Similarly any two levers should have the internal apertures made slightly larger than normal to make it impossible to hold the levers with a central probe.

This device is such that a combination of electronic control within a sealed unit having a minimum of wires together a robust mechanical lock contributes much to auto security.

To initiate the magnetic strip embodiment, the strip is fully inserted into the lock housing at which stage nothing happens other than to operate an initiating switch. The strip must be then withdrawn when readout occurs. This method of operation ensures that the strip cannot be left in the lock whereby security is compromised. From when the strip is fully inserted to the turning ON is completed there is a time feature.

The magnetic strip embodiment may be more expensive than infrared embodiment type, and care with strip alignment must be exercised. The strip is liable to become damaged with use although it would be no problem to carry a spare

in a secure environment. However it is cheaper and easier to replace a damaged or lost strip than an infra-red fob. A damaged strip or circuit failure would not render the vehicle unusable because of the reset facility with the correct key. For vehicle servicing, only the key needs to be handed over, the magnetic security number remaining with the user.

It will be appreciated that although presently described lock is primarily intended for vehicles it can be readily adapted for use in locking high security doors such as on a safe.