WO1988007462A1

WO1988007462A1 - Anti-theft device

Info

Publication number: WO1988007462A1
Application number: PCT/AU1988/000092
Authority: WO
Inventors: Richard Lapinski
Original assignee: Richard Lapinski
Priority date: 1987-04-01
Filing date: 1988-03-28
Publication date: 1988-10-06

Abstract

Disclosed is a vehicle anti-theft device (10, 30) which lockably blocks off the exhaust pipe of the vehicle engine at a point intermediate the length of the pipe. In one form (10) the device includes a gate (12) which is insertable blade-like across the pipe and locked in position by a lock (19) positioned proximate the driver's seat. In an alternative device (30) there is a ball valve (33) rotatable by a rotatable lock (50, 53) via a cable (55, 56). If the cable (55, 56) is cut, a gear (38) is locked by a pin (48) preventing opening of the ball valve (33).

Description

"ANTT-THEFT ΩKVJC.F, " The present invention relates to anti-theft devices specifically adapted for use in motor vehicles and more particularly devices for use in preventing a motor vehicle from being started or run by disrupting the exit of exhaust gases. BACKGROUND ART

There has been considerable interest in the development and use of devices that -are effective in- ^■ ' ^~ minimizing the theft of motor vehicles, particularly cars. The major reason for this interest is that in the recent past, there has been a rapid increase in the rate of car thefts and as the value of the average car has increased considerably, naturally the loss to an owner through car theft has likewise increased.

Accordingly, there are now many devices in the art that function to reduce the possibility of a car being stolen. Broadly, these devices fall into two categories, the electrical and the mechanical. In relation to electrical devices, these generally operate in conjunction with the car's electrical system and range from simple concealed switch devices that prevent the operation of a car's electrical ignition system, to devices that detect any slight movement in the car and respond to same with an audible alarm.

In relation to mechanical devices, these typically function to prevent the operation of an essential mechanical part of the car such as the clutch and the steering wheel, or lock the wheels in place. Although it can be said that many of the prior art devices have a deterrent effect, nevertheless the present inventor believes that the various electrical devices may be defeated by a thief having knowledge of the functioning of such devices. Similarly, it can be said that for many of the mechanical devices, prior knowledge of the devices functioning will allow a thief to defeat its operation.

The applicant in the present case has recognized these limitations in the prior art, particularly in regard to electrical devices and accordingly has sought to achieve a higher degree of protection to theft through the application of a relatively simple but reliable device that acts to make the theft of a car so equipped with the device a slow and difficult task_^ ^: -- - -- - - - DISCLOSURE OF THE INVENTION v . _. ^'■

Accordingly, the present invention consists in an anti-theft device adapted for use in a motor vehicle comprising an exhaust restriction member movable between a openposition in which the flow of exhaust gases from the engine of the motor vehicle is permitted, and a closed position in which the flow of exhaust gas is restricted sufficiently so as to prevent said engine from being started or run, said restriction member being operatively connected to a locking mechanism in a manner such that when said member is in the open position, it may not be readily moved to the closed position and when said member is in the closed position, it is retained and may not be moved into the open position without the release of the locking mechanism. Although the restriction member may be located anywhere in the exhaust system of a motor vehicle, a particularly useful position is in the exhaust pipe as it passes along the underside of the floor proximate the position of the driver. When in such a position, it then follows that the locking mechanism may project from the exhaust pipe through the floor and into the interior of the vehicle. Such an arrangement is particularly convenient as the driver need only in most instances, reach downwardly towards the left to operate the locking mechanism. It will be appreciated by a person skilled in the art that one method of defeating the operation of the present invention would be to disconnect the exhaust pipe from the engine, thereby allowing exhaust gases to escape. Accordingly, in a preferred embodiment of the invention, the exhaust pipe is connected to the engine by way of "shear bolts", that is bolts that must be ground or cut off to effect removal once in place.

Similarly, the device of the invention is preferably fitted to a vehicle's exhaust pipe by way of "shear bolts" or equivalents to discourage the removal of the device or access being gained to allow the exhaust gases to escape.

In order to further reduce the possibility of defeating the device it is preferably positioned in the exhaust system as close as possible to the engine, preferably being attached directly to the exhaust manifold or header pipe set as applicable.

The present inventor believes that in an embodiment of the invention where shear bolts or equivalent are used to protect the connection of both the engine and the exhaust device to the exhaust pipe, a potential thief would either have to cut through the exhaust pipe or the shear bolts, both of which are difficult, time consuming and noisy tasks. Therefore, it is likely that any such action by a thief would tend to attract attention.

In a particularly preferred form, a conventional electronic car alarm capable of detecting undue movement of a vehicle and emitting an audible warning is used in conjunction with the present invention. The advantage of this arrangement is that any attempt by a potential thief to cut the exhaust pipe or remove the shear bolts would activate the conventional alarm and as the time taken to cut through either bolts or exhaust pipes is likely to be prolonged, it is very likely that the thief would not persist given the operation of the audible warning. The dimensions of the exhaust restriction member may be selected from a variety of shapes and sizes depending on the cross-sectional shape and size of the exhaust pipe to which it is to be fitted. In most instances, the exhaust pipe will be circular. Hence that part of the restriction member that projects into the exhaust pipe will generally also be circular. Preferably, the restriction member will be dimensioned so as to substantially restrict the flow o-f exhaust gasesv ^~: It should however be noted that it is not necessarily required to entirely prevent exhaust gas flow. Depending on a variety of" factors such as displacement of the motor vehicle's engine and compression ratio, to prevent the engine from running it may be sufficient to merely reduce the flow of exhaust gases. The extent of reduction required to prevent the running of an engine can be readily determined without undue experimentation by merely selecting, say, a restriction member dimensioned to reduce exhaust flow by 85% and testing the engine to see whether it starts or will run, depending on what is desired. If the engine starts or runs, then the dimensions of the restriction member are increased until the engine either does not start or run. On the other hand, if the engine does not start or run, the dimensions of the restriction member may be reduced appropriately until the engine does start or run.

Generally, the exhaust restriction member will be plate-like in structure of sufficient strength to withstand the pressure of exhaust gas. In particular, the restriction member needs to be of a strength that is able to withstand the force of engine ignition and backfire. To improve the stability of the restriction member when it is in the closed position, supports may be disposed on either face of the restriction member. These supports may each comprise an annular ring fixed to the inner wall of the exhaust pipe and is placed a small distance away from the member. Thus, the restriction member will be adapted to slide between the open and closed positions. The locking mechanism may comprise a housing which connects at a lower end to the exhaust pipe and an upper end projects to at least the underside of the floor of the motor vehicle and a key operated lock connected at a lower end to said restriction-member and- adapted to-siidingly fit within said housing in a manner such that when the key is operated, the lock may be moved sufficiently to cause the restriction member to be locked either in the open or closed position.

Since it will be usual for the length of the housing to be somewhat greater than that of the lock, the lower end of the lock may be provided with a suitable connection to the restriction member. This may be, for example, a metal shaft.

It is preferred that the lock is biassed upwardly into the motor vehicle such that when the key is operated with the restriction member in its closed position, the lock will be forced upwardly. Conveniently, the bias may be provided by a spring mounted within the housing.

In the aforementioned arrangement, it is desirable that means be provided that act to bias the restriction member towards the closed position. Again, conveniently the bias may be provided by a spring mounted within the housing, one end of which bears on the restriction member and the other end on a projection within the housing. The advantage of this arrangement is that any tampering with the lock or the housing will generally result in the restriction member being held in the closed position.

Although it would be expected that under most circumstances no gas or at most an inconsequential amount would leak from this anti-theft device, because of the toxicity of such gases, the housing may be provided with a seal adapted to seal between the housing and the lock and located below the floor of a motor vehicle.

Preferably, at least one vent hole is also provided in that housing intermediate the seal and the lower end of the housing.

Whilst the device of the invention is capable of preventing a motor vehicle having a single exhaust pipe from being started, those vehicles having twin exhaust^* : ^{' " ~} systems may be capable of being started if the device is fitted to only one of the exhaust pipes of the system. Although it could be regarded as inconvenient, such vehicles could be fitted with the device on each of these systems, thereby preventing a so equipped vehicle from being started.

However, the present inventor believes that in a twin exhaust system, even if the device is fitted to only one of the systems _r either the so equipped vehicle engine will not run or at most will run intermittently. From the foregoing description, it will be seen that the anti-theft device of the invention may be readily incorporated into the exhaust system most conveniently of a new vehicle.

However, the device in the engine may also be readily fitted to an existing exhaust system and in this regard the inventor contemplates the components of the device may be sold as a kit of conversion parts, the principal difference being that the device is mounted on a section of pipe adapted to replace a section of the vehicle's fitted exhaust pipe.

Thus, to fit the device to an existing exhaust system, an appropriate length of the exhaust pipe is cut out and a hole drilled in the floor to accept the housing. The device is then placed in the cutout section and appropriately fixed at either of its ends by, for example, muffler clamps held in place by shear bolts. Note that to facilitate the connection of the device to the exhaust pipe, its ends may be flared to fit over the pipe. Alternatively, the device may be welded to the exhaust pipe. Finally, the standard nut and bolt connections to the engine are replaced with shear bolts. BRIEF DESCRIPTION OF THE DRAWINGS

Hereinafter by way of example only is described one embodiment of the invention in which:- Fig. 1 is a longitudinal sectional view of a device of the invention fitted to an exhaust system with the restriction member in its closed position;

Fig. 2 is a longitudinal sectional view of a device of the invention fitted to an exhaust system with the restriction member in its open position;

Fig. 3 is a transverse sectional view about AA of Fig. 2.

Fig. 4 is an exploded view of an alternative embodiment of the invention; Fig. 5 is a schematic representation in sectioned plan view of the embodiment of Fig. 4; and

Fig. 6 is a sectioned elevation of a component of the Fig. 4 and 5 embodiment of the invention. BEST MODE OF CARRYING OUT THE INVENTION The anti-theft device 10 as described hereinafter is adapted to be fitted to a motor vehicle having an existing exhaust system.

Accordingly, the device 10 comprises a tubular portion 13 adapted to be attached to the exhaust pipe 11 via clamps 26 held in place by shear bolts 27, after an appropriate section of the existing exhaust pipe has been removed.

As shown in Fig. 1, the restriction member 12 is a circular plate which in its closed position acts to prevent the passage of exhaust gases along exhaust pipe 11. A pair of angular rings 15 are disposed either side of the plate 12, with a small gap 28 being provided sufficient to permit the plate to be slid between the closed position of Fig. 1 and the open position of Figs. 2 and 3. The locking mechanism is constituted by a housing 14 which extends between the portion 13 and the floor of a motor vehicle 21. At the lower end of the housing 14 there is provided an enlarged..portio -25-adapted to accept plate 12 in its open position. - ^'/ ^' Connected to a lower end of a -shaft 17 is the plate 12 and at an upper end a lock 19.

As shown in Fig. 2, there is ^"a^"spring 20 adapted o, bias the lock 19 upwardly when the plate 12 is in the open position. Similarly, a spring 18 held between plate 12 and annular projection 24 is provided to bias the plate 12 to the closed position. ^;

To reduce the possibility of exhaust gases entering the motor vehicle, an o-ring seal 23 is provided together with vent holes 16.

To operate the device 10, key 22 is inserted into lock 19 and the lock slid downwardly until plate 12 is in the closed position. The lock is then closed, the key removed, thereby preventing the exit of exhaust gases through the exhaust pipe 11 and hence the starting of the motor vehicle's engine.

To move the plate 12 into its open position to permit the vehicle to be started, the procedure is reversed. T?he previously described exhaust valve can be replaced by device 30 shown in Fig. 4. The major components of the device 30 are a body 31, a ball valve 33, a spindle 35, and a gear train 36-38.

The body 31 is attached to the existing exhaust pipe via screw-in flanges 40 and clamps 41. The ball valve 33 is held in sealing co-operation in the interior of the body 31 by annular seals 34. The ball valve 33 has a generally spherical outer surface and a large cylindrical bore hole which can be turned into alignment with the generally cylindrical bore-hole of the body 31, or be turned by the spindle 35 so as to be generally transverse and thus close the exhaust system.

The spindle 35 is controllably rotated by a gear train including a drive gear 36 attached rigidly to the spindle 35, a pinion gear 37 engaging the drive gear 36, and a worm gear^' 38 engaging the pinion 37. The components 36-38 of the gear train are held within appropriate cavities of the body 31 and are covered by a cover plate 42. The cover plate 42 is held rigidly in place by a plurality of screws 43 having Phillips heads which are, after assembly, filled by hammering a ductile ball 44 into the cross slots of the Phillips head of the screws 43.

The worm gear 38 is rotatably driven by a cable 55 carried within an outer cable 56. Attachment 39 is rigid with the outer cable 56 and includes a flange 46. The flange 46 is housed within the slot 45 of the housing 31 so as to hold it fixed to the housing 31 in the generally longitudinal direction of the cable 55.

At the end of cable 55 opposite device 30 is a rotary lock shown in Fig. 5. The rotary lock includes a casing 50 and tumbler 53 fixed relative to each other in their longitudinal direction by protrusions 52. Exiting from the rear of the locking device is a fitting 51 held rigidly to the end of the outer cable 56. The inner cable 55 engages the tumbler 53.

Spring 47 is disposed within the same cavity as worm gear 38 and pressures the worm gear 38 in its longitudinal direction towards the cable 55. The relative lengths of the inner and outer cables 55 and 56 result in the inner cable 55 protruding sufficiently into the cavity of the worm gear 38, when the complete device is assembled, so as to compress the spring 47 and move the proximate end of the worm gear 38 some distance from the flange 46. If part of the locking device is disturbed or the cable 55/56 cut then the inner cable 55 can no longer sustain the compressive force and the worm gear 38 is pushed by the spring 47 until it abuts the flange 46. When this occurs, as seen in Fig. 6, a. locking pin 48 engages under spring tension a suitably- sized- hole- 49

The locking pin 48 is. held- with^'iii a. cavity 54 disposed within the cover plate 42 and thus prevents any further movement of the worm gear 38. By this means if the device is disturbed when the ball valve 33 is in the closed position, the complete device 30 must be disassembled in order to open the valve 33 thus making it difficult to bypass the security operation of the device.

Claims

CLAIMS : -

1. An anti-the t device adapted for use in a motor vehicle comprising an exhaust restriction member movable between a open position in which the flow of exhaust gases from the engine of the motor vehicle is permitted, and a closed position in which the flow of exhaust gas is restricted sufficiently so as to prevent said engine from being started or run, said restriction member being operatively connected to a locking mechanism in a manner such that when said member is in the open position, it may not be readily moved to the closed position and when said member is in the closed position, it is retained and may not be moved into the open position without the release of the locking mechanism.

2. An anti-theft device as defined in claim 1 wherein the exhaust restriction member comprises a housing adapted to normally allow the flow of exhaust gas through an internal passage thereof, and a ball valve located intermediate of the internal passage and being rotatable through an angle from an open position to a closed position, the ball when in the open position includes a passageway generally aligned with, and of similar diameter to, the internal passage of the housing, and in the closed position the ball valve substantially or entirely prevents the flow of exhaust gas through the internal passage of the housing.

3. An anti-theft device as defined in claim 2 wherein the ball valve is rotatably driven by a gear train within a gear cavity of the housing, the gear train being rotatably driven by a rotatable locking device positionable remote of the housing.

4. An anti-theft device as defined in claim 3 wherein the gear train includes a worm gear driven by a cable from the locking mechanism, the worm gear being biased axially toward the cable by a worm gear spring, the cable comprising an inner and outer cable wherein the inner cable can resist compressive load and the inner and outer cable are of relative lengths such that upon assembly the inner cable compresses the worm gear spring and forces the worm gear axially away from the cable beyond a first axial position the housing including a spring loaded pin transverse of the worm gear and the worm gear including a transverse hole which aligns with the spring loaded pin when the ball valve is closed and the worπr gea__rris"^"±ιr the^"-^" first axial position such that- if the cable- ±s^~ removed "aτrd^r the ball valve is closed the pin will move into the transverse hole and lock the worm gear stationary relative to the housing.

5. An anti-theft device as defined in claim 2 further including an annular seal at each axial end of the ball valve sealing the exterior of the ball valve to the interior of the housing.

6. An antitheft device as defined in claim 1 or 2 when fixed to and intermediate of a vehicle exhaust system.