Title
Automatic engine cut-off switch for automobiles using mechanical SPDT limit switches during Re-fuelling.
Field of invention
The invention relates to the fabrication of an automatic engine cut-off system for enhancing the safety of automobiles during times of re-fuelling operations. This helps to minimize the chances of fire hazards occurring at the time of re-fuelling due to heat and static electricity.
Background of invention
Automobiles are to be turned off at the time of re-fuelling operations. But because of the discomfort caused, many drivers hesitate to turn their vehicles off. Many Case studies showed that static charges and heat are the main phenomena for fire accidents happening at fuel stations. Spark Ignition Engines may ignite the fuel fumes around the fuel stations by leaking spark. Spark plug wires might be sparking and cause the fuel to ignite. Turning off the vehicle ignition is the best practice to reduce the chances of fire hazards.- Hence, an automatic cut-off switch integrated with the fuel lid opener and fuel gate will automatically turn off the vehicle ignition. Vehicle fueling stations are usually built in crowded areas, urban, suburban and on the highways, where there is a huge amount of traffic. Fire sources are a means of complex hazard particularly when the oil and gas are going in and out of the vehicle refuelling stations. The presence of flammable gas and liquid leads to cause fire hazards and there is a greater risk of causing casualties in case of fire and explosion. Safe distance has to be maintained between the equipment in refuelling stations and the building (structure) outside of the stations, and the safe distance shall comply with vehicle refuelling stations design and construction specifications requirements. Also for reducing the static electricity generation the connection from the fuel dispenser to the fuel outlet should be continuous. From this device, we can reduce the chances of fire hazards in fuelling stations.
Summary of the invention
A limit switch (5) is an electromechanical device that consists of an actuator mechanically linked to a set of contacts. When an object comes into contact with the actuator,

the device operates the contacts to make or break an electrical connection. The system consists of an SPDT relay cut-off switch (7), and mechanical SPDT limit switches (5 & 6) connected with the fuel lid (3) and the fuel lid opener (4) respectively. The mechanical limit switches (5 & 6) have to be installed on both the fuel lid opener (4) and the fuel lid (3). When the fuel lid opener (4) is actuated, the mechanical limit switch (6) placed on the fuel lid opener (4) will break the Normally Closed (NC) circuit control in the limit switch (6). This will make the circuit to Normally Open (NO) condition and the supply to the ignition coil is interrupted with the help relay cut-off switch (7). Due to a lack of electrical supply to the spark plugs the ignition of the vehicle will be turned off. When the fuel lid opener (4) is released, the supply to the ignition coil is resumed and the vehicle can be turned on. To prevent the vehicle to be turned on during refuelling additional safety system i.e mechanical limit switch (5) is provided in the fuel lid (3) also. When the fuel gate (3) opens, a mechanical force is given to the limit switch (5) which changes the circuit to Normally Open (NO) condition. Since the system is connected in series, the received signal to the relay cut-off switch makes the circuit turn off the ignition system when the fuel lid (3) is in open condition. Once the fuel lid (3) is closed, the circuit changes to Normally Closed (NC) condition and the supply to the ignition coil is resumed and the vehicle can be turned on. Thus the vehicles cannot be turned on during the fuelling operations, by this system and thus reducing the chances of fire hazards during the fuelling process in fuel stations. And the system is cost-effective and uses a simple circuit setup system and enhances the safety of the vehicle.
Brief description of several views of drawings
Fig. 1 is the schematic view of the present invention. Fig. 2 is the schematic view of the mechanical SPDT limit switch. Fig. 3 is the schematic view of the SPDT Cut-Off Relay. Reference numerals in the drawings
1 Battery 5 Mechanical SPDT Limit Switch
2 Ignition Key 6 Mechanical SPDT Limit Switch
3 Fuel Lid 7 SPDT Cut-off Relay
4 Fuel Lid Opener 8 Wire

A detailed description of the invention
. The present invention depicts an automatic engine cut-off system in order to prevent safety hazards in automobiles at the time of re-fuelling. The invention helps in preventing hazardous situations at the time of re-fuelling because of static electricity and heat.
Figure. 1 shows a schematic view of the present invention in the form of a circuit. Battery (1) is connected with the SPDT cut-off relay (7) and the ignition key (2) using wires (8). When fuel lid (3) is opened, it will disconnect the connection between ignition (2) and battery (1). The power is disconnected using a mechanical SPDT limit switch (5). Similarly, when the vehicle is in ON condition, to open the fuel lid (3) on the vehicle, we need to actuate the fuel lid opener (4). When the fuel lid opener (4) is actuated; this fuel lid opener (4) is coupled with a mechanical SPDT limit switch (6) and hence the circuit is disconnected that will turn off the vehicle ignition. The mechanical SPDT limit switches (5) and (6) are connected with the SPDT cut-off relay (7) for providing 2-way safety to prevent the ignition of the vehicle during re-fuelling. Figure. 2 shows the schematic view of the mechanical SPDT limit switch comprising a common terminal point, a normally open contact (NO), a normally closed contact (NC) and a mechanical actuator. This mechanical SPDT limit switch has its initial position in any one of the contacts i.e. is either NO or NC. Whenever the mechanical actuator is actuated, it changes its position from the previous position. Figure. 3 shows the schematic view of the SPDT Cut-Off Relay.