The use of magnetism in the fuel injector
Before we can begin to look at the operation of the Fuel injector it is important to have an understanding of some important magnetic principles i.e
A magnet contains what is known as magnetic lines of force or field lines however these are invisible to the naked eye. Magnets vary in shape, size, strength etc.
These field lines radiate from each end of a bar magnet. Each end is polarised i..e. one being the North Pole and the other being the South Pole. Field lines flow from North to South. The strength of these field lines is what determines the strength of the magnet. These magnetic field lines will flow easier through a piece of electromagnetic material than through air.
- Principles of Magnets
- Principles of Electromagnetism
- Principles of Magnets:
A magnet contains what is known as magnetic lines of force or field lines however these are invisible to the naked eye. Magnets vary in shape, size, strength etc.
These field lines radiate from each end of a bar magnet. Each end is polarised i..e. one being the North Pole and the other being the South Pole. Field lines flow from North to South. The strength of these field lines is what determines the strength of the magnet. These magnetic field lines will flow easier through a piece of electromagnetic material than through air.
Interesting things happen if two magnets are brought close together.
- If the magnetic poles are the same, they repel
- if the magnetic poles are opposite, they attract
2. Principles of Electromagnetism
When a current is made to flow in a piece of wire it generates a circulating magnetic field about a wire. The direction of the magnetic field will depend on the direction of the current flow in the wire. the magnetic field will depend on the direction of the current flow in the wire. The magnetic field goes clockwise when viewed from the direction of the current.
When a current is made to flow in a piece of wire it generates a circulating magnetic field about a wire. The direction of the magnetic field will depend on the direction of the current flow in the wire. the magnetic field will depend on the direction of the current flow in the wire. The magnetic field goes clockwise when viewed from the direction of the current.
- If we produce a coil from this wire the magnetic field from each of the turns in the coil add together, so the total magnetic field is much stronger. A soft iron core will concentrate the lines of magnetic field inside the coil, turning the coil into an electromagnet containing a North and South Pole
- The current in the diagram on the left will flow left. If we reverse the direction of the current flow we then reverse the North and South Poles.
What happens in the Electronic Fuel injector?
The way the EFI functions is very simple: when electrical current is applied to the terminals, the armature which is pressed against the valve seat by the return spring is attracted by the solenoid poles and moves up towards them reaching the stop. This movement causes an opening at the metering section where the pressurized fuel passes and as soon as it leaves the valve it is pulverized into fine droplets. When the electrical excitation stops, the magnetic attracting force diminishes very quickly and the armature is pushed against the valve seat by the action of the return spring, closing the fuel passage.
The way the EFI functions is very simple: when electrical current is applied to the terminals, the armature which is pressed against the valve seat by the return spring is attracted by the solenoid poles and moves up towards them reaching the stop. This movement causes an opening at the metering section where the pressurized fuel passes and as soon as it leaves the valve it is pulverized into fine droplets. When the electrical excitation stops, the magnetic attracting force diminishes very quickly and the armature is pushed against the valve seat by the action of the return spring, closing the fuel passage.