Micro-controlled Fuel Management System

Field of the Invention:

This invention relates to "Micro-controlled Fuel Management System" and more particularly for a vehicle with a spark ignition IC engine.

Background of the Invention:

Natural gas is known to have many advantages when used as a engine fuel source. Natural gas is a clean burning fuel which lowers overall emissions. It may also be used as a fuel without the addition of the additives required in gasoline, for example which often includes heavy metals. Generally the technologies used for converting spark ignition engines to operate on gaseous fuels are mechanically controlled systems. Such mechanical systems are incapable of meeting modem vehicle requirements. In particular they fail to provide the responsiveness, power, or fuel efficiency and emissions expected by the customers or regulatory norms.

Apart from the mechanically controlled system, electronic controlled systems are also available. These electronic controlled systems work with in conjunction with the original equipment control unit. Actually they are typically provided with two separate electronic control units, one for controlling the gasoline and the other for natural gas. In this kind of two separate control unit arrangement, a signal from one control unit is utilized as input for other control unit. A mode selection unit will be present to select the gasoline mode or natural gas mode.

There are several drawbacks to this approach. One of the principle drawbacks is that involving two separate controllers turns out to be quite expensive. In addition to this it increases the part counts thereby making the system complex.

In view of the above discussed problems, it is clear that significant work has been made in systems for converting liquid fuelled engines to operate on gaseous fuels, an economical conversion system which fulfills the engine performance expectations in modern vehicle application has not been realized yet.

Summary of the Invention:

It is an object of the invention to provide a micro controlled fuel management system for utilization of gaseous fuels in spark ignition engines which can be tailored to engines employing closed loop system, more particular to three wheeler vehicle and two wheeler vehicle.

It is a further object of the invention to provide a microcontroller for utilization of gaseous fuel in spark ignition engines which generates an engine ignition control signal for gasoline as well as gaseous fuel in response to plurality of the sensors for sensing selected engine conditions.

It is a further object of the invention to provide a microcontroller for utilization of gaseous fuel in spark ignition engines which generates a fuel control signal to control the gaseous fuel delivery to the engine.

It is a further object of the invention to provide a micro-controlled fuel management system in which the pressure of the natural gas stored in the cylinder is reduced in one step to be delivered to mixer.

It is yet a further object of the invention to provide a micro-controlled fuel management system which is enabled with a fuel control valve, which delivers the quantity of fuel to the engine through the mixer, in response to the fuel control signal from the micro-controller.

It is also an object of the invention to provide a micro-controlled management ignition system which is cost effective, and this objective is achieved by reducing the part counts.

It is a further object of the invention to provide a micro-controlled management ignition system which is capable of reducing the part counts and this objective is achieved by utilizing one electronic controller for both gasoline and gaseous fuel.

It is also an object of the present invention to provide a micro-controlled fuel management system which is simple in operation and arrangement, and yet gives the desired performance levels which is required for a modem vehicular application.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Brief description of the Drawings:

The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein

Figure 1 shows a schematic drawing according to one of the preferred embodiments of the present invention.

Detail Description of the Drawings:

Referring to figure 1, the present invention provides a fuel management system that includes a micro- controller 101 for controlling the operation of a spark ignition engine to operate on a gaseous fuel and gasoline fuel. The said micro-controller 101 accepts outputs from a plurality of sensors for sensing selected engine conditions and generates primarily spark control signal for both gasoline and gaseous fuel. It also generates a fuel control signal 102 in response to the sensor(s) output for fuel delivery of gaseous fuel. This closed loop system enables the micro-controller to achieve maximum engine performance and fuel efficiency while minimizing engine exhaust emissions.

The said spark engine is equipped with a intake manifold which is supplied with liquid fuel or gaseous fuel as per the driver's requirement. The liquid fuel is supplied from a gasoline tank in a manner well known in the art. Preferably the liquid fuel from the gasoline tank travels through the conventional carburettor to reach the intake manifold of the engine. The spark ignition engine is also equipped with a spark control module which controls the ignition spark generation by a spark plug in engine cylinder. The spark ignition engine is also equipped with an exhaust system from where an oxygen sensor outputs a signal representative of the oxygen content of the exhaust gases is fed back to the micro-controller, to function in a closed loop system.

It should be understood that while the spark ignition engine includes a closed loop control system, the micro-controller in accordance with the invention is equally adapted to operate with engines having open loop system.

The micro-controller accepts inputs from a plurality of sensors and outputs variety of control signals for operating gasoline as well as gaseous fuel. In order to enable operation, the said micro-controller must receive output signals from at least exhaust gas oxygen sensor 103, an engine coolant temperature (ECT) signal 104, speed of revolution of engine (RPM) 105, throttle position signal (TPS) 106, a battery voltage 107. The said micro-controller can be adapted to receive some more inputs like inputs from oil pressure switch 108 for optimal performance.

The said TPS input 106, RPM input 105, ECT input 104 and oxygen sensor 103 signal are all received by the said micro-controller on separate lines. In accordance with a preferred embodiment of the micro-controlled fuel management system the compressed natural gas (CNG) 110 is supplied to the CNG/ AIR mixer 109 by a one stage pressure reduction. The pressure reduction of the CNG is done preferably by a pressure reduction unit 111, which is electronically controlled. The said pressure reduction unit 111 maintains the pressure of the CNG at a desired level. After the pressure is reduced it is made to flow throw a filter 112 and then is fed to a fuel control valve 113. The said fuel control valve 113 is preferably a servomotor based control.

The said microcontroller after receiving the inputs from various sources, outputs a fuel control signal 102 to the said fuel control valve 113 and accordingly the corresponding quantity of fuel is delivered to CNG/AIR mixer 109 through low pressure hose 114. From the mixer 109 the fuel travels through the conventional carburettor 115 to the engine intake manifold. When the CNG mode is selected by the driver of the vehicle, the gasoline line is stopped and the conventional carburettor acts as a mere throttle device for the CNG fuel coming from the mixer.

The said microcontroller also outputs spark control signal 116 for both CNG and gasoline fuel. In addition to fuel control and spark control signal the microcontroller can be adapted to provide various outputs which will cater to the requirements like speed density calculation 117, fuel level indication 118, malfunction indicating lamp' 119, Bi fuel application 120, waste spark elimination 121, timing efficiency calculation 122, engine over-speed cut off 123, instantaneous mileage indicator 124, data logging and graphing, engine speed limiting with engine temperature, low fuel lamp, catalyst temperature modelling etc.

A safety function 125 output from the micro-controller is preferably provided to CNG pressure reduction unit, for any emergency safety requirements, which if required will close the CNG flow from the CNG cylinder. Means for checking the protocol 126 is also provided in the microcontroller. ECM hardware is made available for OBD2/EOBD diagonistics.

The net effect of this innovation is to permit the use of one microcontroller where prior art systems would require two or more controllers. Besides the obvious cost benefit, reducing the number of controllers to single controller has trickle down benefits of simplifying fuel management system complexity.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the claims.

We Claim:

1. A micro-controlled fuel management system for spark ignition engine having a microcontroller to operate interchangeably on gasoline and gaseous fuel comprising:

means for accepting signals from a plurality of sensors for sensing selected engine operating conditions;

means for generating on the basis of sensed engine operating conditions, a spark control signal adapted for gasoline and gaseous fuel;

means for generating on the basis of sensed engine operating conditions, a fuel control signal adapted for gaseous fuel;

means for initiating a gasoline fuel operating mode and terminating a gaseous fuel mode in response to mode selection input; and

means for initiating gaseous fuel operation and terminating gasoline fuel operation in response to mode selection input.

2. A micro-controlled fuel management system as claimed in claim 1, wherein the micro controller determines at least the following:

engine coolant temperature;
battery voltage;
the speed of revolution of engine;
throttle position signal; and
oxygen exhaust gas.

3. A micro-controlled fuel management system as claimed in claim 1, wherein the micro controller further determines at least the following:

speed density;
fuel level;
malfunction indicator;
timing efficiency;
waste spark elimination;
instantaneous mileage; and
engine over speed cut-off.

4. A micro-controlled fuel management system as claimed in claim 1, wherein the said microcontroller generates a fuel control signal for the fuel control valve for gaseous fuel.

5. A micro-controlled fuel management system as claimed in claim 4, wherein the said fuel control valve is preferably a servo motor based control.

6. A micro-controlled fuel management system as claimed in claim 1, wherein the said microcontroller provides a provision for checking the protocol.

7. A micro-controlled fuel management system as claimed in claim 1, wherein the system is adapted for two wheeled vehicle.

8. A micro-controlled fuel management system as claimed in claim 1, wherein the system is adapted for three wheeled vehicle.