Antitheft Alarm System for Motor Vehicles

This invention relates to an antitheft alarm system for motor vehicles.

The number of vehicle thefts is increasing. In order to counteract these thefts, antitheft alarm systems are known which become operative when there is unauthorized access to the vehicle or violent acts are carried out against it. A number of useful device are available for this purpose.

It is an object of the invention to further develop these devices with the goal of improving the protection of motor vehicles against theft.

According to the invention, this object is achieved by providing a device for triggering an alarm system in the event of a change of the position of the vehicle.

The principal advantages achieved by means of the invention are that, in the event of a change of the position of the motor vehicle, for example, when it is attempted in an unauthorized manner to load the vehicle onto a truck by means of a fork lifter, the device will trigger the warning system. As a result, the attempted unauthorized act is interrupted or at least made difficult at an early stage. The device, which is equipped with a compass, is highly effective and can be implemented at reasonable expenditures, in that it may also be integrated into an existing alarm system which becomes operative, for example, in the case of an unauthorized access to the vehicle. Finally, the device, which consists of the compass and a control apparatus, may be installed as a constructional unit into an existing motor vehicle.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

FIG. 1 schematically depicts the antitheft alarm system for motor vehicles according to preferred embodiments of the present invention; and FIG. 2 is a flow chart according to the present invention.

A motor vehicle is equipped with an alarm system 1 which comprises an alarm control device 2 which is triggered in the case of an unauthorized change of the position of the motor vehicle in the horizontal directions. Embodiments are also contemplated where the alarm is triggered for vehicle movement in the vertical direction. Thus, any change in position of the vehicle triggers the alarm.

The device 2 comprises a control apparatus 3 and a compass 4 having a compass needle 5. Other devices than a compass which have the same effect of detecting vehicle movement are also contemplated for other non-illustrated embodiments. The control apparatus 3 has an ignition lock 6 with an ignition key 7 and a warning device 8 which emits acoustic signals. It may also be constructed such that visual signals are emitted. In addition, the control apparatus 3 is provided with an electrical/electronic device 9 for the management of an internal combustion engine 10. The device 2 is supplied with current at reference number 11.

For securing the motor vehicle, the ignition key 7 is withdrawn and the doors--not shown--are locked. As a result, an actual position value of the motor vehicle, which is defined by the compass needle 5, is stored in the control apparatus 3. If an attempt is made now to change the position of the motor vehicle in an unauthorized manner, for example, by means of a fork lifter, the compass needle 5 will deflect, whereby the control apparatus 3 determines a deviation from the stored position value and immediately activates the warning device 8. FIG. 2 is a flow chart illustrating this operation. At the same time, the device 9 for the engine management is influenced such that the start of the operation of the internal-combustion engine 10 will be prevented.

Although the invention has been described and illustrated in detail, it is to be clearly understood that the same is by way of illustration and example, and is not to be taken by way of limitation. The spirit and scope of the present invention are to be limited only by the terms of the appended claims.