Background of the Invention
The present invention relates in general to engine disabling and more paticularly concerns novel apparatus and techniques that coact with a vehicle alarm to disable the engine upon the occurrence of an alarm condition and thereby help prevent the vehicle from being stolen.
It is an important object of the invention to provide improved means for disabling an engine to help prevent vehicle theft. It is another object of the invention to achieve the preceding object with reliable apparatus that is relatively free from complexity.
It is still a further object of the invention to achieve one or more of the preceding objects while preventing normal beeping of a vehicle horn that is also used to provide an audible indication of an alarm condition from disabling the engine.
It is another object of the invention to achieve one or more of the preceding objects while providing a convenient means for enabling the engine.
Summary of the Invention
According to the invention, there is relay means having one end of a relay winding connected to a source of operating potential and the other end connected to an alarm output through a unilaterally conducting device poled to allow current to flow through the relay winding when the alarm output is at a potential corresponding to the existence of an alarm condition, such as being grounded. This alarm output terminal is connected to the vehicle horn relay through unilaterally conducting means poled to allow the flow of current through the horn relay when the alarm output is at a potential corresponding to an alarm condition, such as ground potential. There are holding contact means connected between the winding other terminal and a common terminal through normally closed reset switching means for keeping the relay means operated until the reset switching means is opened following the occurrence of an alarm condition. The relay means also includes at least an additional set of contacts for electrical connection to the engine for disabling engine operation when the relay is operated. Preferably, the relay means includes a number of redundant sets of contacts to insure reliable operation and preferably includes both normally closed and normally open contacts to accommodate a wide variety of engine disabling conditions.
Numerous other features, objects and advantages of the invention will be better understood from the following specification when read in connection with the accompanying drawing.
Brief Description of the Drawing
The single FIGURE of which is a schematic circuit diagram of a preferred embodiment of the invention.
Detailed Description of Preferred Embodiments
With reference now to the drawing, there is shown a schematic circuit diagram of a preferred embodiment of the invention in which occurrence of an alarm condition on alarm output terminal 11 operates relay RL1 to interconnect common terminal 12 and normally open contacts terminal 13 while disconnecting common terminal 12 and normally closed contacts terminal 14. The normally closed contacts may be connected in series with the ignition circuit to prevent the spark plugs from firing when the relay is operated or may be in series with an electrically operated fuel pump to prevent the delivery of fuel when the relay is operated. Alternatively, terminals 12 and 13 may be connected across the primary of the ignition transformer to prevent the spark plugs from being ignited. These terminals may be otherwise connected to the engine to prevent and permit operation when relay RL1 is operated and not operated, respectively.
One end of the winding 15 of relay RL1 is connected to the vehicle battery potential, typically twelve volts, on terminal 16. The other end is connected through holding contacts 17 and reset switch S1 to ground. This end 18 is also connected by diode D1 to the alarm output terminal 11. Alarm output terminal 11 is connected to horn relay terminal 21 by diode D2. These diodes coact so that upon occurrence of an alarm condition both diodes conduct to operate the horn relay and relay RL1, and once relay RL1 is operated, holding contacts 17 maintain it in the operated condition until switch S1 is opened. Switch S1 may be concealed in the vehicle so that only the vehicle operator readily knows its location for deenergizing relay RL1 and allowing the engine to operate. If the horn relay connected to terminal 21 is operated by the horn ring, diode D2 prevents the grounding of terminal 21 from operating relay RL1. Diode D1 prevents the ground connected to winding end 18 through switch S1 and latching contacts 17 from operating the horn relay.
The use of three redundant contacts minimizes the chances that the engine will be disabled because of defective relay contacts.
There has been described novel apparatus and techniques for disabling an engine upon occurrence of an alarm condition and preventing restoration until the vehicle operator operates a concealed reset switch. The apparatus is rugged, reliable and economical. It is evident that those skilled in the art may now make numerous uses and modifications of and departures from the specific embodiments described herein without departing from the inventive concepts. Consequently, the invention is to be construed as embracing each and every novel feature and novel combination of features present in or possessed by the apparatus and techniques herein disclosed and limited solely by the spirit and scope of the appended claims.