AUTOMOTIVE BURGLAR ALARM HAVING BATTERY CURRENT FLOW DETECTOR

• US 3,706,966 A
• Filed: 12/07/1970
• Issued: 12/19/1972
• Est. Priority Date: 12/07/1970
• Status: Expired due to Term

• Current Assignee: Reinhold Mueller, Richard T. So
• Original Assignee: Reinhold Mueller, Richard T. So
• Inventors: So, Richard T., Mueller, Reinhold
• Primary Examiner(s): Waring, Alvin H.
• Application Number:
  US05/095,829
• Time in Patent Office: 743 Days
• Field of Search: 340/63,64,65,253P,248P,253R,276 307/10
• US Class Current: 340/428
• CPC Class Codes: B60R 25/1004 Alarm systems characterised by the type of sensor, e.g. current sensing means using door lock sensors B60R25/1001

Abstract

An alarm device is energized when any current is drawn from the battery employed in the electrical system of the automotive vehicle. The onset of battery current is utilized to produce a voltage pulse, which is employed to trigger a silicon controlled rectifier. The rectifier energizes a relay coil which operates relay contacts connected to the alarm device. The voltage pulse preferably is produced by a magnetic pickup coil mechanically coupled to the battery cable of the electrical system. In a second embodiment, the instantaneous battery voltage is compared with the stable voltage across a capacitor charged to the initial battery voltage. Any drop in the instantaneous voltage produces a voltage pulse which triggers the electronic switch. In a third embodiment, two of the leads to the silicon controlled rectifier are connected to the negative battery cable between the negative battery terminal and ground, between which an SCR triggering voltage drop develops when current is drawn from the battery. In each of the embodiments, if the SCR is bypassed initially, it is connected to be latched by avalance operation. The burglar alarm can be encapsulated as a module and can be coupled electrically into the vehicles'"'"''"'"' electrical system easily, without any splicing of existing wiring. The magnetic pickup coil of the primary embodiment is subject to sensitivity regulation by way of a clamp which mounts and orients the module with respect to the battery cable.

Claims

1. A burglar alarm for an automotive vehicle of the type having an electrical system, including a battery having internal battery resistance, battery terminals and cables, and at least one electrical utilization device, with a control switch between the battery and the utilization device, said burglar alarm comprising:

an electronic switching component having electrodes;

a current change sensitive means in the form of a magnetic pickup coil positioned closely adjacent to one of said battery cables, and thus alined within the magnetic field of said one battery cable, yet not directly electrically connected to said one battery cable or across said battery terminals;

said pickup coil being responsive to an expanding magnetic field around said one battery cable, induced by the onset of current from the battery to at least one of said utilization devices in the electric system, for producing a voltage pulse;

said pickup coil being connected in a series loop between two different of said electrodes of said electronic switching component for supplying the said voltage pulse to trigger said electronic switching component;

the construction of said pickup coil and its connection within said burglar alarm being such that the production of its said voltage pulse is independent of the internal battery resistance;

an alarm device; and

an output circuit connected between said electronic switching component and said alarm device, for actuating said alarm device in response to the triggering of said electronic switching component.

2. A burglar alarm according to claim 1 in which said electronic switching component comprises a silicon controlled rectifier;

and said output circuit includes;

a relay coil and shutoff switch connected in series with the main electrodes of said silicon controlled rectifier, energizing leads constructed for connection to the electrical system of the vehicle, and relay contacts operable by said relay coil for energizing said alarm device.

3. A burglar alarm according to claim 2 in which at least one said utilization device comprises a switch connected so as to shunt said rectifier and having one side connected to said relay coil, whereby closing of said switch actuates said alarm in lieu of triggering said rectifier, and reopening of said switch causes said relay coil to drive said rectifier into an avalanche mode of operating for continuing the actuation of said alarm.

4. A burglar alarm according to claim 3 in which said pickup coil is connected between the control electrode and one of the main electrodes of said rectifier, and the shunting switch is connected between said one main electrode and the other of the main electrodes of said rectifier.

5. A burglar alarm according to claim 1 in which said electrical system includes an illumination bulb simulating circuit for drawing current from said battery as a selectively enabled utilization device and comprising, a parallel connected resistor and capacitor.

6. A burglar alarm according to claim 1 in which said pickup coil is encapsulated, mechanical clamping means is provided for mounting said encapsulated coil onto said one battery cable, and said clamping means is constructed and arranged for orientation of said pickup coil in various positions of magnetic sensitivity with respect to the magnetic field around said battery cable.

7. A burglar alarm for an automotive vehicle of the type having an electrical system, including a battery, battery cables and at least one utilization device, with a control switch between the battery and the utilization device, said burglar alarm comprising:

an electronic switching component, input means coupled to the electrical system for supplying a voltage pulse to trigger said electronic switching component in response to the onset of current from the battery in the electrical system, said input means comprising a pair of input leads connected to two spaced points along one of the battery cables in the electrical system, between which a voltage drop is produced when current is drawn from the battery, said leads being connected to the electronic switching component to apply thereto said triggering voltage pulse, an alarm device, and an output circuit connected between said electronic switching component and said alarm device, for actuating said alarm in response to the triggering of said electronic switching component.

8. A burglar alarm according to claim 7 in which said electronic switching component comprises a silicon controlled rectifier, and said leads are connected to the control element and one electrode of said silicon controlled rectifier, so that the rectifier is triggered by a voltage drop between said leads.

9. A burglar alarm according to claim 8 in which said output circuit comprises a relay coil and a shutoff switch connected in series with said rectifier, and relay contacts operable by said relay coil and connected to said alarm device.

10. A burglar alarm according to claim 9 in which at least one said utilization device comprises a switch connected so as to shunt said rectifier and has one side connected to said relay coil, whereby closing of said switch actuates said alarm in lieu of triggering said rectifier, and reopening of said switch causes said relay coil to drive said rectifier into an avalanche mode of operating for continuing the actuation of said alarm.

11. A burglar alarm for an automotive vehicle of the type having an electrical system, including a battery and at least one utilization device, with a control switch between the battery and the utilization device, said burglar alarm comprising:

an electronic switching component, input means coupled to the electrical system for supplying a voltage pulse to trigger said electronic switching component in response to the onset of current from the battery in the electrical system, said input means comprising means for noting the initial battery voltage in the electrical system when current is not being drawn from the battery and means for comparing the instantaneous battery voltage with the initial battery voltage to produce said voltage pulse when the instantaneous voltage drops due to any current being drawn from the battery, an alarm device, an output circuit connected between said electronic switching component and said alarm device for actuating said alarm device in response to triggering of said electronic switching component said input means further comprising energizing leads constructed for connection to the electrical system to receive the voltagE therein due to the battery, a storage capacitor, means connected to said leads for charging said storage capacitor to the initial battery voltage while preventing rapid discharge of said capacitor, and said means for comparing comprising means for comparing the instantaneous battery voltage across said leads with the voltage across said storage capacitor to derive a voltage pulse due to the instantaneous voltage drop when current is drawn from the battery.

12. A burglar alarm according to claim 11 in which said electronic switching component comprises a silicon controlled rectifier having its control element connected to said comparing means, so that the rectifier is triggered by said voltage pulse.

13. A burglar alarm for an automotive vehicle of the type having an electrical system, including a battery and at least one utilization device, with a control switch between the battery and the utilization device, said burglar alarm comprising:

an electronic switching component, input means coupled to the electrical system for supplying a voltage pulse to trigger said electronic switching component in response to the onset of current from the battery in the electrical system, said input means comprising means for noting the initial battery voltage in the electrical system when current is not being drawn from the battery and means for comparing the instantaneous battery voltage with the initial battery voltage to produce said voltage pulse when the instantaneous voltage drops due to any current being drawn from the battery, an alarm device, an output circuit connected between said electronic switching component and said alarm device for actuating said alarm device in response to triggering of said electronic switching component;

a storage capacitor;

means including a diode for charging said storage capacitor to the initial battery voltage, said diode preventing rapid discharge of said capacitor; and

in which said electronic switching component comprises a silicon controlled rectifier, said output circuit comprises a relay coil connected in series with the main electrodes of said rectifier, and relay contacts operable by said coil and connected to said alarm device, said input means comprises leads constructed for connection to the electrical system to receive the battery voltage at a point in the system subject to voltage drop due to battery current, and said means for comparing comprises means for comparing the instantaneous battery voltage with the voltage across said capacitor.

14. A burglar alarm according to claim 13 in which at least one said utilization device comprises a switch connected so as to shunt said rectifier and having one side connected to said relay coil, whereby closing of said switch actuates said alarm in lieu of triggering said rectifier, and reopening of said switch causes said relay coil to drive said rectifier into an avalanche mode of operating for continuing the actuation of said alarm.

15. A burglar alarm according to claim 14 which further comprises an electronic control component having one control element connected to said capacitor and another control element connected to one of said leads to receive the instantaneous battery voltage, and said comparing means includes a coupling circuit between said electronic control component and the control element of said silicon controlled rectifier, to supply said triggering voltage pulse thereto in response to a drop in the battery voltage due to current being drawn from the battery.

16. A burglar alarm according to claim 1 in which at least one said utilization device comprises a switch connected so as to shunt said electronic switching component and has one side connected to said output circuit, whereby closing of said shunt switch directly actuates said alarm in lieu of triggering said electronic switching component, and reopening of said switch causes said output circuit to generate a voltage trAnsient to drive said electronic switching component into an avalanche mode of operating for continuing the actuation of said alarm.