GB1577812A

GB1577812A - Preventing unauthorised use of vehicles

Info

Publication number: GB1577812A
Application number: GB23945/77A
Authority: GB
Original assignee: TELCEFO SECURITY PRODUCTS AB
Current assignee: TELCEFO SECURITY PRODUCTS AB
Priority date: 1976-06-08
Filing date: 1977-06-08
Publication date: 1980-10-29
Also published as: BE855455A; IE44968B1; DE2725808A1; IT1082101B; NL7706277A; FR2354455A1; ES459590A1; CA1096255A; SE7606432L; IE44968L; AT358333B; SE404159B; ATA403377A; AU2594977A; AU508331B2; JPS5317804A; DK253077A

Description

(54) PREVENTING UNAUTHORISED USE OF VEHICLES.

(71) We, TELCEFO SECURITY PRODUCTS AB, of Elektravägen 53, S-126 30 Hägersten, Sweden, a Swedish joint stock company organised under Swedish law, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement This invention relates to a device for immobilising a spark-ignition internal combustion engine, by preventing the unauthorised re-insertion of a removed spark plug. The expression "immobilising" is intended to mean rendering the engine wholly or partially inoperable, it being appreciated that a multicylinder engine may require the removal of more than one spark plug to prevent it working at all. In this case more than one device may be used, or reliance may be placed on the malfunctioning of an engine with one plug missing. Alternatively, reliance may be placed on an optional feature of the device of the invention which will cause damage to the engine if an attempt is made to start it with the device in place.

The principal object of the invention is therefore to provide a device which will wholly or partially incapacitate a spark-ignition internal combustion engine to make difficult or impossible the unauthorised removal by means of the engine of the vehicle or boat propelled by the engine, even if the controls of the engine are accessible and the ignition circuit is complete. Competent car thieves find it relatively easy to gain access to a locked car and short-circuit the ignition.

Steering or gear lever locks have not proved adequate. In the case of boats, a lock which prevents the removal of an outboard motor will not prevent theft of the entire boat. If, however, the engine itself is incapacitated the removal of the vehicle or boat which it propels becomes more problematical, and in the case of outboard motors an engine which could not be used would not attract a thief.

In accordance with the invention there is provided a device for immobilising a sparkignition internal combustion engine, comprising a housing relatively rotatably connected to an externally screw-threaded plug portion extending from the housing, and a lock operable to engage the housing to the plug portion for joint rotation, the arrangement being such that a spark plug of an engine can be replaced by the device, the plug portion being screwed into the vacated spark plug bore until it is inaccessible for counterrotation except by means of the housing, the lock being operable to engage the housing and plug portion for joint rotation when it is desired to unscrew the plug portion from the bore by rotating the housing.

The housing is preferably tubular and the lock is preferably located inside the housing.

The lock may be of the barrel type and is preferably rotatable relative both to the housing and the plug portion when unlocked.

The lock may have bolts received in recesses respectively in the housing and the plug portion when locked, and the lock may be spring-loaded to a locked condition and unlockable against the spring loading by a key.

The housing and plug portion may be rotatably connected by a spring ring received in annular recesses respectively in the inner periphery of the housing and the plug portion.

The plug portion may have a free end section designed to extend into the associated cylinder when the plug portion is screwed into a spark plug bore so as to contact a piston reciprocated in said cylinder. Said free end section may be pointed to adapt it to damage said piston, and it may be removable from the remainder of the plug portion so that its use is optional.

The housing is preferably of polygonal external shape to adapt it to be rotated by a plug spanner.

The housing is preferably manufactured from hardened steel, such as carbide steel.

Preferred embodiments of the invention will now be described with reference to the accompanying drawings, in which:-- Figure 1 is a sectional elevation of a device in accordance with the invention mounted in a spark-plug bore of an engine cylinder head, Figure 2 is a plan view of the device of Figure 1, Figure 3 is a view similar to Figure 1 but showing the device in the locked condition, and Figure 4 is a view similar to Figure 1 of a modified device.

The device illustrated in Figures 1-3 comprises a tubular housing 1 of hardened steel, such as carbide steel, relatively rotatably connected to an externally screwthreaded plug portion 2 by means of a ring 3 of spring steel which is located in a peripheral groove in the internal wall of the housing 1 and a peripheral groove around the shank of the plug portion 2 above its screw-thread.

Located in the housing 1 is a barrel-type lock 4 which has bolts or pins 5 which, under the influence of a key 6, can be made to extend from the lock, pins 51 extending radially into recesses in the inner wall of the housing 1 and pins 511 extending axially into recesses in the top of the plug portion 2. In this way the lock 4 can be made to interconnect the housing 1 and plug portion 2 for joint rotation, but in the unlocked condition (to which the pins 51 and 511 are preferably spring-biased) the lock 4 is freely rotatable relative both to the housing 1 and the plug portion 2 and therefore the housing 1 is freely rotatable relative to the plug portion 2.

The manner of use of the device is as fol lows:- Having removed a spark plug (not shown) from the cylinder head the plug portion 2 is screwed in its place. Conveniently, and as shown in Figure 2, the housing 1 is polygonal so that a plug spanner can be used to screw the device into a plug bore. The device is screwed in until the plug portion 2 is inaccessible exteriorly of the engine and can only be counter-rotated by means of the housing 1.

The lock 4 is now unlocked, so that if the housing 1 is turned in an attempt to unscrew the plug portion 2 all that will happen is that the housing 1 will rotate relative to the plug portion 2. This condition of the device is shown in Figure 3. When it is desired to remove the device and re-insert the sprk plug the key 6 is used to operate the lock 4 so that by turning the housing 1, e.g. with a plug spanner, the plug portion 2can be-unscrewed.

Ih the embodiment of Figures 1-3, the free end of the plug portion 2 terminates in a pointed projection 7 designed to extend into the cylinder where it will contact the piston if this reciprocates in the cylinder with the device in situ. The resulting damage to the engine will immobilise it even if it is of a multi-cylinder type which would not be fully incapacitated by the removal of a single spark plug.

The embodiment of Figure 4 is similar in all respects to that of Figures 1-3 except that the pointed projection 7 on the free end of the plug portion 2 is removable therefrom by unscrewing it before the device is used if this feature of the device is not desired. With the projection 7 removed the free end of the plug portion 2 is flush with the inner surface of the cylinder head and will not damage the piston.

WHAT WE CLAIM IS: 1. A device for immobilising a sparkignition internal combustion engine, comprising a housing relatively rotatably connected to an externally screw-threaded plug portion extending from the housing, and a lock operable to engage the housing to the plug portion for joint rotation, the arrangement being such that a spark plug of an engine can be replaced by the device, the plug portion being screwed into the vacated spark plug bore until it is inaccessible for counter-rotation except by means of the housing, the lock being operable to engage the housing and plug portion for joint rotation when it is desired to unscrew the plug portion from the bore by rotating the housing.

2. A device as claimed in claim 1, wherein the housing is tubular and the lock is located inside the housing.

3. A device as claimed in claim 2, wherein the lock is of the barrel type and is- rotatable relative both to the housing and the plug portion when unlocked.

4. A device as claimed in any one of the preceding claims, wherein the lock has bolts received in recesses respectively in the housing and the plug portion when locked.

5. A device as claimed in any one of the preceding claims, wherein the lock is springloaded to a locked condition and can be unlocked against the spring loading by a key: 6. A device as claimed in any one of the preceding claims, in which the housing and plug portion are rotatably connected by a spring ring received in annular recesses respectively in the inner periphery of the housing and the plug portion.

7. A device as claimed in any one of the preceding claims, wherein the plug portion has a free end section designed to extend into the associated cylinder when the plug portion is screwed into a sprk plug bore so as to contact a piston reciprocated in said cylinder.

8. A device as claimed in claim 7, wherein said free end section is pointed to adapt-it to damage said piston.

9. A device as claimed in claim 7 or claim 8, wherein said free end- section is removable from the remainder of the plug portion.

10. A device as claimed in any one ofthe preceding claims, wherein the housing, is of polygonal external shape to adapt it to be rotated by a plug spanner.

11. A device as claimed in any one of the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. in accordance with the invention mounted in a spark-plug bore of an engine cylinder head, Figure 2 is a plan view of the device of Figure 1, Figure 3 is a view similar to Figure 1 but showing the device in the locked condition, and Figure 4 is a view similar to Figure 1 of a modified device. The device illustrated in Figures 1-3 comprises a tubular housing 1 of hardened steel, such as carbide steel, relatively rotatably connected to an externally screwthreaded plug portion 2 by means of a ring 3 of spring steel which is located in a peripheral groove in the internal wall of the housing 1 and a peripheral groove around the shank of the plug portion 2 above its screw-thread. Located in the housing 1 is a barrel-type lock 4 which has bolts or pins 5 which, under the influence of a key 6, can be made to extend from the lock, pins 51 extending radially into recesses in the inner wall of the housing 1 and pins 511 extending axially into recesses in the top of the plug portion 2. In this way the lock 4 can be made to interconnect the housing 1 and plug portion 2 for joint rotation, but in the unlocked condition (to which the pins 51 and 511 are preferably spring-biased) the lock 4 is freely rotatable relative both to the housing 1 and the plug portion 2 and therefore the housing 1 is freely rotatable relative to the plug portion 2. The manner of use of the device is as fol lows:- Having removed a spark plug (not shown) from the cylinder head the plug portion 2 is screwed in its place. Conveniently, and as shown in Figure 2, the housing 1 is polygonal so that a plug spanner can be used to screw the device into a plug bore. The device is screwed in until the plug portion 2 is inaccessible exteriorly of the engine and can only be counter-rotated by means of the housing 1. The lock 4 is now unlocked, so that if the housing 1 is turned in an attempt to unscrew the plug portion 2 all that will happen is that the housing 1 will rotate relative to the plug portion 2. This condition of the device is shown in Figure 3. When it is desired to remove the device and re-insert the sprk plug the key 6 is used to operate the lock 4 so that by turning the housing 1, e.g. with a plug spanner, the plug portion 2can be-unscrewed. Ih the embodiment of Figures 1-3, the free end of the plug portion 2 terminates in a pointed projection 7 designed to extend into the cylinder where it will contact the piston if this reciprocates in the cylinder with the device in situ. The resulting damage to the engine will immobilise it even if it is of a multi-cylinder type which would not be fully incapacitated by the removal of a single spark plug. The embodiment of Figure 4 is similar in all respects to that of Figures 1-3 except that the pointed projection 7 on the free end of the plug portion 2 is removable therefrom by unscrewing it before the device is used if this feature of the device is not desired. With the projection 7 removed the free end of the plug portion 2 is flush with the inner surface of the cylinder head and will not damage the piston. WHAT WE CLAIM IS:

1. A device for immobilising a sparkignition internal combustion engine, comprising a housing relatively rotatably connected to an externally screw-threaded plug portion extending from the housing, and a lock operable to engage the housing to the plug portion for joint rotation, the arrangement being such that a spark plug of an engine can be replaced by the device, the plug portion being screwed into the vacated spark plug bore until it is inaccessible for counter-rotation except by means of the housing, the lock being operable to engage the housing and plug portion for joint rotation when it is desired to unscrew the plug portion from the bore by rotating the housing.

5. A device as claimed in any one of the preceding claims, wherein the lock is springloaded to a locked condition and can be unlocked against the spring loading by a key:

6. A device as claimed in any one of the preceding claims, in which the housing and plug portion are rotatably connected by a spring ring received in annular recesses respectively in the inner periphery of the housing and the plug portion.

11. A device as claimed in any one of the

preceding claims, wherein the housing is manufactured from hardened steel.

12. A device for immobilising a sparkignition internal combustion engine substantially as herein described with reference to and as shown in Figures 1-3 or Figure 4 of the accompanying drawings.