A multi-point gas injection system, said to be `the best marriage between petrol and LPG’, enables the car’s original engine management system to control the fuel mix and gas flow.
There are a number of advantages for using liquid petroleum gas (LPG) as a fuel for powering vehicles. Benefits include lower CO emissions and it is cleaner for cold start and short distance traffic. It is said that one diesel car produces the same amount of polluting particles as 10 LPG powered cars. Unfortunately service stations selling the fuel in this country are rather limited, restricting the number of vehicles using the system, so the reliance is still for petrol.
Fuel management systems are developing very rapidly. The ideal would be a system that is capable of handling both fuels. With the introduction of On Board Diagnostics (OBD) it is essential to integrate with the original fuel management system.
This had been the impetus for Prins Autogassystemen to develop YPS – its multi-point gas injection system, that ensures optimal conditions for good communication, by integration of the gas system in the petrol fuel management. The development is also based on the requirement to meet the most strict emission standards, as the right of gas systems to exist depends on their advantages for the environment. The YPS system is applicable to LPG or CNG on multi-point fuel injection engines with catalytic converter.
In operation the gas/liquid flows from a storage tank via a high pressure fuel line through an electromagnetic lock-off valve to the single stage converter/evaporator. The concept is suitable for engines up to 250hp. The gas pressure is +/-1.4bar which ensures good cold starting behaviour.
The gas flows from the converter to the gas flow metering unit. The delivery of the required gas flow is effected by positioning a specially developed plunger, whose position is calculated by the YPS fuel management and set by a proportional solenoid. As the positioning of the plunger is electronically closed loop controlled, the gas flow metering is fast and accurate, the pressure drop over the metering device is constant and the system pressure low.
Gas then flows to the pressure regulator, which ensures that the gas flow metering is not influenced by manifold air pressure and divides the total gas flow between the cylinders. The division of the total gas flow is very accurate, as has been proven by the variation of emissions per cylinder being minimal and demonstrably better than on petrol.
Gaseous fuel is injected into each cylinder in the inlet manifold, where possible at the locations of the petrol injectors.
The quantity of gas is derived from and controlled by the engine’s original fuel management system. The YPS computer translates the required petrol demand into a demand for gas. To account for factors such as differences in physical properties between petrol and gas and its consequences for metering, corrections are made by the YPS fuel management system. The petrol fuel management lambda control system also controls the YPS system and the OBD system continues to operate both on petrol and gas.
Prins Autogassystemen Tel: +31 (40) 254 77 00