ENGINE IMMOBILISATION SYSTEMS

Abstract: An engine immobilisation system comprises a blockage device (18) operable in the exhaust duct (24) of the engine aspiration system at a location close to the engine to cause a reverse flow of gas to choke the engine. Blockage is effected by a high-temperature resistant blockage member (34) operating in a manner similar to a butterfly valve and actuated by a flexible drive cable. An electronic control system (48) actuates a stepper motor (42) to control blockage in accordance with sensed vehicle parameters including detection of unauthorised use of the vehicle.

Description: ENGINE IMMOBILISATION SYSTEMS This invention relates to a method and apparatus for engine immobilisation applicable to the immobilisation of internal combustion engines including both diesel and petrol engines, and indeed engines using other fuels and fuel forms. An important aspect of the invention relates to the use of an engine immobilisation system as part of a vehicle security system. The invention is concerned with an engine immobilisation system utilising blockage means for the exhaust portion of the engine aspiration system. Such a device has significant advantages over other vehicle security systems including alarms, steering locks, brake locks and ignition cut-outs. However, previous proposals for engine immobilisation systems have related to the provision of blockage devices at the tail end or discharge end of the exhaust system of an internal combustion engine. Examples of such disclosure are • _„__, GB-A-22 24 539A and GB-A-21 36 873A and GB-A-21 93 531A and GB-A-21 86 911A. Such proposals suffer from several significant shortcomings including a lack of security since, as a practical matter, it would be relatively easy to remove such a device by simply sawing off the tail end portion of the exhaust pipe, using a hacksaw. In any case, these devices are not effective to immobilise an engine since the volumetric capacity of the exhaust system on the upstream side of the immobilisation device is such that the engine can start even when the device is in place and blocking the exhaust system. The engine then acts as a gas pump and severe damage can result both to the engine and to associated systems. The gas pressures developed are sufficient to blow out gaskets in the exhaust system and the reverse direction gas flow resulting from the blockage can cause serious damage to a catalytic convertor. Accordingly, it can be seen that these prior proposals are subject to significant shortcomings in terms of ability to resist determined attempts to remove or otherwise render inoperable the immobilisation device, and otherwise. An object of the present invention is to provide an engine immobilisation system offering improvements in relation to one or more of the matters discussed above, or generally. According to the invention there is provided a method and apparatus for engine immobilisation as defined in the accompanying claims. In an embodiment of the invention, by the provision of blockage means controllable to adopt, selectively, blocking and non-blocking conditions the advantage is provided that the apparatus can remain permanently in place, without the need for awkward and inconvenient and otherwise unacceptable operations needed for bringing the prior art proposals mentioned above into use and out of use. In an embodiment of the invention also, control means for the blockage means is provided and located outside the duct means and is actuable to effect change of the blockage means between its blocking and non-blocking conditions. In this way, remote control of the blockage means can be provided in a convenient manner, and indeed a secure manner since the blockage means itself can be conveniently actuated even though it is located in an inaccessible location so that it is relatively invulnerable to the attentions of would-be thieves. Likewise in an embodiment of the invention, the blockage device is mounted at a location upstream of the discharge end of the exhaust duct. In this way, the operation of the device is significantly improved in relation to the prior art proposals in that, by virtue of the proximity of the device to the engine, a reverse flow of gas is generated which chokes the engine, rather than causing a build-up of back pressure as tends to occur with the prior art proposals. Thus, the invention provides an engine immobilisation system in which means is provided for blocking or otherwise preventing or interrupting the outward flow of exhaust gases from an internal combustion engine, at a location upstream of the discharge end of the exhaust system of the engine. In one embodiment, the blockage means is in the form of valve means, for example a butterfly valve. By providing the blockage means in the form of a valve, the valve being incorporated in the pipe of the exhaust system of the engine, and the valve being actuable by external means, there is provided a system whereby the exhaust pipe itself can operate either to immobilise the engine, or to permit the engine to run. By providing the blockage means upstream of the discharge end of the exhaust system, the blockage means is rendered relatively inaccessible in most cars/automobiles, and thus is rendered relatively tamper-proof. In the embodiment, a butterfly-type valve is employed which enables valve control to be exercised by external means in a relatively straightforward manner. Alternative valve means could be employed, such as an iris valve, but it is expected that gas control will be less straightforward than in the case of a butterfly-type valve. Likewise, it might be possible to incorporate a ball or other types of valve provided adequate space were available. In the embodiment the material of the disc of the butterfly-type valve is 316 grade stainless steel, which is the preferred material as of the date of filing of this application, even with respect to ceramic materials, which are well known for their thermal resistance characteristics. In an embodiment, the blockage means is supplied in the form of a replacement length of tubing, incorporating the valve means, for incorporation into the exhaust system of an internal combustion engine. The length of tubing can be simply bolted into place as a replacement for a short length of the existing exhaust system. In the embodiment, means is provided for setting the valve of the blockage means automatically to its valve-closed blockage condition when the user switches off the engine. This is made a feature of the valve control system, whereby automatic engine security is provided. Furthermore, the valve drive is arranged to operate in the case of a power interruption so as to fail to the state of the valve in which the power interruption occurred, whereby safety is greatly increased as compared with vehicle immobilisation systems such as those acting on the transmission or the brakes which can have significant safety shortcomings in the event of power failure. The blockage device can be fitted readily into vehicles otherwise than as original equipment, for example during routine service work or replacement of parts of the exhaust system, or merely as a replacement of a short section of the main pipe of that system. The blockage device is particularly ef ective in relation to diesel engines. It may be fitted at any convenient location on the downstream side of the engine exhaust valves. The usual location would be some little distance from the exhaust manifold at the location where the exhaust pipe passes under the floor of the passenger compartment of the vehicle, whereby direct action of flames from the exhaust valves on the butterfly valve disc is prevented by the intervening change of direction in the pipe. In the embodiment, the butterfly-type valve disc is controlled by a flexible shaft coupled to an electric stepping motor. Alternative control systems are of course possible. The exhaust blockage means may be provided as one of several security systems provided in a single motor vehicle. In an embodiment described below in which a touch memory recognition device is provided in order for the blockage device (or indeed, other alternative or additional security devices) to be caused to adopt their operation-permitted condition, the advantage is provided that the mobile touch memory element, which the user utilises as a "key" to deactivate the immobilisation system, does not itself require a battery or other source of power, and is effective in this way for the entire life of the equipment. The position of the blockage member or valve member is controlled in an embodiment by a powerful microprocessor which monitors the status of the vehicle, including the engine, and other information, to determine the appropriate state for the blockage member. Safety features are incorporated which ensure that the blockage member can never be closed if the engine is running. The microprocessor automatically closes the blockage member when the engine is switched off and the authorised driver leaves the vehicle. In the embodiment, the blockage or valve member does not need to form a perfect seal with the walls of the duct due to the fact that the immobilisation of the engine is caused by reverse flow of gas choking the engine. As the blockage member is located close to the engine exhaust manifold, in most cases it is not possible for the engine to start before it is choked. If it does start, it will die almost immediately. In another embodiment the blockage device is provided in the inlet side of the aspiration system at a position immediately upstream of the exhaust manifold so as to be able, in its blocking condition, to interrupt the supply of air and fuel mixture to the combustion chambers. For inlet-side control, some variation in the location of and/or application of the invention to differing kinds of engines using differing fuels (and thus differing fuel/air mixture supply systems) will be necessary. In the case of an inlet-side blockage member the high temperature requirements do not arise and therefore construction can be simplified and relatively cheaper. For many applications, the blockage member may comprise a disc of 16 gauge and 316 grade stainless steel. For higher performance engines a blockage member formed as a ceramic pressing is to be preferred. In a modification, a pivoted- plate type valve member is used in place of a butterfly disc and the plate member is of generally rectangular profile and located in a complementary rectangular section profile duct. The plate member is pivoted about an axis adjacent to one side wall of the duct. An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which :- Fig 1 shows a diagrammatic representation of an internal combustion engine having an exhaust manifold connected to an exhaust aspiration system comprising a silencer and, on the upstream side thereof, an engine immobilisation device; Fig 2 is a diagrammatic representation of functions provided in a control system for the engine immobilisation device of Fig 1; Fig 3 and 4 show sections through the engine immobilisation device of Fig 1 on the line III-III therein, and showing, respectively, a blockage device in its blocking and non-blocking positions; and Fig 5 shows, on a larger scale, a section through the engine immobilisation device indicating its open and closed positions. As shown in the drawings, engine immobilisation apparatus 10 for connection to the aspiration system 12 of an internal combustion engine 14 comprises duct means 16 and blockage means 18 therein. The blockage means is controllable to adopt, selectively, blocking and non-blocking positions shown in Figs 3 and 4 respectively. Control means 20 is located outside duct 16 and changes the blockage means between its blocking and non-blocking positions. As shown in Fig 1, the blockage means 18 is located upstream of the discharge end 22 of exhaust duct 24, and likewise upstream of a silencer or catalytic converter/silencer assembly 26 therein. As shown in Fig 1, engine 14 comprises an exhaust manifold 28 connected in a conventional manner to exhaust duct 24 which comprises a downwardly sloping portion 30 and a generally horizontal portion 32. This latter portion has silencer 26 incorporated therein, and may be profiled in any suitable manner to accommodate vehicle construction requirements. Duct 16 is incorporated into portion 32 of exhaust duct 24, but could be incorporated in portion 30 thereof, equally. In Fig 1, for clarity and simplicity of illustration, duct means 16 is indicated as if it were of considerably larger diameter than exhaust duct 24. However, in practice this is not the case, and duct 16 is just of slightly larger diameter than the exhaust duct, so as to be a tight sliding fit thereover, as a replacement for a short section thereof. It is welded to the exhaust duct, to form a gas-tight seal thereto. As shown in Figs 3, 4 and 5, blockage member 18 is in the form of a disc 34 mounted for pivotal movement about an axis 36 on a rod 38. The rod and the disc are of stainless steel and the rod is located in a diametral groove (not shown) pressed in the disc to accommodate it. In use, disc 34 is movable between its closed and open positions shown in Figs 3 and 4, and likewise in Fig 5. Movement of the disc between its open and closed positions is effected by means of a flexible shaft drive 40 which transmits drive from a stepping motor 42 through a torque step-up reduction gear box 44, and thus to disc 34. Shaft drive 40 is coupled to the disc through a coupling 46. A control module 48 receives inputs from sensors 50, 52 sensing, respectively, engine operation and vehicle door open or closed positions. A user identification module 54 provides an input indicating whether the user is authorised or not. Further inputs and outputs may be provided and there is shown a crank inhibit device 56 which operates to inhibit the engine starter motor in the event of attempted unauthorised use. Annunciator module 58 provides output indicating either visually or by means of audible signals the status of the security system and the engine immobilisation apparatus 10. Control module 48 comprises a microprocessor of known construction to analyse the identified inputs for functions in accordance with the stated parameters and operations, including outputs to control motor 44 and modules 56, 58. The user identification module 54 comprises a Dallas semiconductor Micro-PROM unit encased in a small metal "can" roughly the shape and size of a lithium calculator battery which is used as a "key" in association with a reader unit. Control module 48 is arranged to permit use of the system only upon recognition of the previously identified user from this "key" . This system provides a high degree of security in terms of very precise identification of user and inoperability of the system without such identification. Alternative key systems may be employed. In this embodiment, the micro-PROM unit is available under serial number DS1990 from the range of Dallas semi-conductor Touch Memories. In use, the user simply makes contact between the "key" and its complementary reader unit. Upon recognition, a system permission-to-operate signal is generated. In use, the above described system provides a high level of effectiveness of engine immobilisation in association with the parameters of the security system shown in Fig 2. A high degree of resistance to mechanical attack arises from the location of the blockage device at a relatively inaccessible point. Other advantages are provided as mentioned previously. In a further embodiment, not specifically illustrated as such, the blockage means is provided in the inlet side of the engine instead of on the exhaust side. The blockage device is located immediately upstream of the inlet manifold so as to be able to interrupt the flow of air/fuel mixture to the inlet ports of the engine. The blockage device may be constructed generally as ' described above, but in this case there is no requirement for high temperature resistance, and therefore modification of the materials used can be adopted. In this embodiment the immobilisation of the engine is produced on a simple fuel/air starvation basis. The blockage device and its control systems are otherwise constructed and arranged as described above.

Claims: CLAIMS : - 1 Engine immobilisation apparatus for connection to the aspiration system of an internal combustion engine comprising a) duct means to form part of the exhaust side of said aspiration system to transmit exhaust stroke gases from the engine; b) blockage means effective to block the passage of said exhaust stroke gases, said blockage means being located within said duct means; and c) said duct means being adapted to be mounted or located on the exhaust side part of said aspiration system, thereby to immobilise said engine; characterised by d) said blockage means being controllable to adopt, selectively, blocking and non-blocking conditions; e) control means for said blockage means and located outside said duct means and actuable to effect change of said blockage means between its blocking and non-blocking condition; and f) said duct means being mounted or adapted to be mounted on said exhaust side part of said aspiration system at a location upstream of the discharge end of said exhaust par . 2 Engine immobilisation apparatus for connection to the aspiration system of an internal combustion engine characterised by blockage means for the exhaust or inlet side of said aspiration system and controllable to adopt, selectively, blocking and non-blocking conditions. 3 Apparatus according to claim 1 or claim 2 characterised by said blockage means being adapted to be located or provided with instructions for mounting at a location between said engine and exhaust gas treatment means such as a catalytic converter or silencer. 4 Apparatus according to claim 3 characterised by said blockage means being adapted to be mounted nearer to said engine than to said exhaust gas treatment means thereby rapidly to choke the engine in use. 5 Apparatus according to any one of claims 1 to 4 characterised by said duct means being adapted to be inserted into the duct of said exhaust side of said engine aspiration system to replace a short length thereof. 6 Apparatus according to any one of the preceding claims characterised by said blockage means comprising a blockage member permanently located in said duct means and mounted for angular movement between blocking and non-blocking positions. 7 Apparatus according to claim 6 characterised by said blockage member being constructed and mounted in the manner of the valve member of a butterfly valve. 8 Apparatus according to claim 6 or claim 7 characterised by said control means being connected to said blockage member and comprising a drive to turn said blockage member, and engine status verification means being provided to prevent operation of said drive and of said blockage member during normal operation of the engine. 9 Apparatus according to any of the preceding claims characterised by said apparatus being installed in a vehicle with said blockage means being located at a relatively inaccessible location chosen from within the engine compartment or below the body of the vehicle, and said control means for said blockage means being coupled to said blockage means by a flexible drive cable arranged to transmit drive to said blockage member from remote actuation means. SUBSTITUTESHEET 10 A vehicle security system comprising apparatus according to any one of the preceding claims in combination with vehicle status sensing means associated with said control means to distinguish between authorised and non-authorised use of said vehicle, and adapted to cause said control means to change said blocking means to its blocking condition upon detecting attempted non-authorised use of the vehicle. 11 A method of engine immobilisation comprising providing duct means to form part of the exhaust or inlet side of the aspiration system of an internal combustion engine, and blockage means being provided to block passage of exhaust or inlet gases through said duct means, characterised by the step of actuating said blockage means, selectively, to adopt blocking and non-blocking conditions according to requirements for immobilisation or non-immobilisation respectively. SHEET

Inventors: DRAKE PAUL DAVID, DRAKE, PAUL, DAVID
Applicants: DRAKE PAUL DAVID, DRAKE, PAUL, DAVID
Application year: 1993
Main classification: B60R25
IPC codes: B60R25, F02B1