This invention relates to a fuel injection system for motor vehicles, particularly, though not exclusively, for two wheeler and three wheeler motor vehicles.
Fuel injection systems are increasingly bemg used in internal combustion engines to replace the carburettor mainly m order to comply with em ission norms as well as to achieve better fuel economy
The known fuel injection system requires a power source e.g. a battery or generator to work the fuel pump for increasing the fuel pressure. If the battery is run down the fuel pump cannot create sufficient pressure at the injector and the vehicle cannot be started. On the other hand if the system is designed to work without a battery it has to use a high power generator, to generate the required output during kick starting, which is expensive.
The object of this mvention is to propose a fuel injection system which can be operated, even when thw battery is run down, and without use of a high power generator. Once the engine starts, the generator of the vehicle provides the necessary power to the fuel pump to run the engine.

Various features of the fuel injection system proposed herein will be apparent from the following description given hereunder.
The fuel injection system for a motor vehicle, according to this invention, comprises a fuel pump for connection to a source of electric power, fuel tank and regulator; an injector for connection to a controller and to die fuel pump through a fuel line, characterised in that a nonreturn valve is provided in the fuel line; an accumulator is also provided in the fuel line between the non-return valve and the injector, the accumulator storing air entrapped under pressure exerted by the fuel in the fuel line; and an air lamp connected to the accumulator, said air pump having a one way outlet and being m anually operable to increase the pressure of the air entrapped in the accumulator.
This invention will now be described with reference to the single Figure in the accompanying drawings which illustrates, by way of example, and not by way of limitation, one of various possible embodiments of the fuel injection system proposed herein.
A fuel pump F is connected to a source of electric power P, usually a battery and generator, or a generator, a fuel tank T and fuel pressure regulator R.

The iuel from the lank T is pumped by the i'uel pump F, through a fuel line L, to an injector I whence the fuel passes on to the controller C to the engine. The regulator R sends fuel, pumped by the fuel pump F, exceeding a given pressure value, back to the fuel tank T.
According to the above mentioned arrangement, whenever the battery is run down, and the engme is OFF, there is no sufficient power to operate the fuel pump F. In the absence of a battery, the power from the magneto (generator) obtained by kick starting the vehicle may not also be sufficient to operate the fuel pump. Consequently die engine cannot be started.
To meet such a situation, this invention proposes a nonreturn valve V in the fuel line L, which allows fuel from the fuel pump F, into the fuel line L, along the direction of the arrow A, to the mjector I, but which prevents the flow of fuel in the other direction, that is to say, along the direction of the arrow B.
This invention also proposes an accumulator E in the fuel line L. Air is entrapped in the accumulator at M by the fuel 0 in the fuel line L. This entrapped air is under pressure from the fuel G in the fuel line L, during normal running of the engine.

Now, when the engine is OFF and required to be started, with the battery in run down condition, although the fuel pump F does not build up the requisite pressure in the fuel line L, the pressure of the entrapped air at M in the accumulator supplies the requisite pressure to force the fuel G m the fuel line L through the injector I and start the engine. When the engine is OFF the pressure of the entrapped air at M is retained mside the accumulator E since the fuel in the fuel line L is prevented from leavmg the fuel line m the direction of the arrow B and, at the same time, is also prevented from leaving the fuel line in the direction of the arrow A by the injector I. Once started, the generator of the vehicle takes over to operate the fuel pump F and run the engine in the normal way. During prolonged storage without operation of the vehicle the pressure in the accumulator E can reduce due to leakage. To overcome this situation the pressure of the entrapped air in the accumulator can be increased by manually operating an air pump Q provided for the accumulator. This pump has a one way outlet so that the air pumped out from the pump Q into the accumulator E in the zone Z of the entrapped air does not return; and thus the pressure of the entrapped air within the accumulator is increased to permit better flow of fuel in the fuel line into the injector I. The air pump will

preferably be provided with a spring loaded push button Y for the manual operation of the pump.
The terms and expressions herein are of description and not of limitation, inasmuch as various other embodiments of the fuel injection system proposed herein are possible without departing from the scope and ambit of this invention.

We Claim:
1. A fuel injection system for a motor vehicle comprising a fuel pump for connection to a source of electric power, fuel tank and regulator; an injector for connection to a controller and to the fuel pump through a fuel line, characterised in that a non-return valve is provided in the fuel line; an accumulator is also provided m the fuel line between the non-return valve and the injector, the accumulator storing air entrapped under pressure exerted by the fuel in the fuel line; and an air pump connected to the accumulator, said air pump having a one way outlet and being manually operable to increase the pressure of the air entrapped in the accumulator.
2.A fuel injection system for a motor vehicle as claimed in Claim 1 wherein the air pump is provided with a spring loaded push button.
3.A fuel injection system for a motor vehicle as claimed in Claim lor Claim 2 wherein the source of electric power is a battery.
4 A fuel injection system for a motor vehicle as claimed m any one of the preceding Claims wherein the source of electric power is a generator. 5. A fuel injection system for a motor vehicle substantially as herein described with reference to, and

88 illustrated in, the accompanying drawings.
Dated this 22nd day of March 2004
INDIA NIPPON ELECTRICALS LIMITED