|Title of Invention||
"AN IMPROVED FUELLING DEVICE FOR AN INTERNAL COMBUSTION ENGINE"
|Abstract||An improved internal combustion engine comprising a piston assembly in a cylindrical combustion chamber connection to a crank shaft having exhaust ports at its two ends; and fueling device connected to the said combustion chamber, wherein the said fueling device comprises a fuel pump and a valve connected thereon, said valve being controlled by electronically controlled means.|
|Full Text||The present invention relates to an internal combustion engine comprising a piston assembly in a cylindrical combustion chamber connected to a crank shaft having exhaust ports at its two ends and a fueling device connected to the said combustion chamber. The main embodiment of the present invention resides in the fueling device which is an electronically controlled continuous fueling device. The main embodiment of the present invention resides in the ability to apply the continual fueling control as against the cyclic fueling control.
BACKGROUND OF THE INVENTION
The simple but inefficient mixture scavenged, spark ignition engines are used for a wide variety of utility engines, mopeds, motor cycles, for lawn and garden equipment such as chain saws, leaf blowers, trimmers and the like; smaller motorcycle engines used on dirt bikes, jet skis, small outboard motors as well as radio controlled model planes. These two stroke spark ignition engines find effective usage in two wheelers because of important advantages over four stroke engines viz., two stroke spark ignition engines do not have valves which simplifies their construction and they fire once every revolution while four stroke engines fire once every other revolution, giving two stroke spark ignition engines a significant power boost. These advantages make two stroke spark ignition engines lighter, simpler and less expensive. Besides being cost effective the two stroke spark ignition engines also have the potential to pack about twice the power into the same space because there are twice as many power strokes per revolution. The combination therefore gives two stroke spark ignition engines a greater power to weight ratio.
The principal advantages of the spark ignition engines are higher specific power output, lower specific weight and volume, simpler construction, lower brake specific NOx emission and lower part load pumping losses.
The spark ignition engines however suffer from major disadvantages as well. These disadvantages specifically relate to efficient usage of fuel. The spark ignition engines produce a lot of pollution which comes from two sources. The first is the
combustion of oil and the other reason is that every time a new charge of air/fuel is loaded in the combustion chamber, part of it leaks out through the exhaust port. The high specific hydrocarbon emission and the generally inferior fuel consumption of mixture scavenged spark ignition engines are largely due to the direct loss of air fuel mixture to the exhaust during the open cycle. This is further accentuated by impaired combustion due to high dilution. These emissions not only contribute to causing pollution hazard but also decreases fuel efficiency.
Therefore a need arises for fuel efficient engine which overcomes the drawbacks pertaining to fuel efficiency and pollution hazard.
The lowest displacement capacity in the single cylinder version in the current scenario of spark ignition engine is about 35CC. These are crankcase mixture scavenged and are generally constant speed machines. In the 50-250cc capacity, in the single cylinder version they are used in the transport vehicle application and are generally crankcase mixture scavenged variable speed load machines. However, here direct loss of fuel air mixture during scavenging, high dilution of charge through out the range of engine operating conditions and in particular at low throttle operation, and petrol lubrication are principal factors responsible for high brake specific fuel consumption and emission.
The 250CC and above capacity multicylinder engines are yet to be developed for automotive application. Here, however, the direct loss of fuel air mixture during scavenging is fully eliminated in systems employing in-cylinder injection in the closed part of the cycle and reduced substantially in those employing in-cylinder injection in the open part of the cycle. Independent lubrication system is employed to achieve more efficient lubrication system of the engine. However, these engines also suffer from the drawbacks of high dilution which has a negative impact on the engine performance.
The air breathing capacity of crankcase scavenged two-stroke engine is known to be limited by the volumetric efficiency (delivery ratio) characteristic of the
crankcase. At full throttle the best figure achieved is around 60 percent in a predetermined (3000-3500 RPM) speed range of engine operation. With the inevitable through-put loss of a substantial part of this during scavenging (upto 30-35% at full throttle and 15-20% under idling), a considerable part of the combustion product of the previous cycle is carried forward and dilutes the fresh mixture of the operating cycle. The proportion of the residual products could be as high as 80% under low throttle condition and almost around 50% even under full throttle operation. The high dilution in spark ignition crankcase mixture scavenged spark ignition engines is the fundamental factor contributing to high emission under low speeds and the torque trough at low speeds. The problem of high dilution persists in conventional stroke engines, single or multicylinder, constant or variable speed type.
In a mixture scavenged spark ignition engine, the scavenging of the residual combustion products at the end of each cycle of engine processes is carried out by a pre mixed charge of fuel and air. This necessarily involves loss of fuel and air, referred to as "short circuiting" of fresh charge.
Besides, dilution and short circuiting, another problem encountered in the conventional engines relates to direct mixture loss. Cause of such direct mixture loss is scavenging of the combustion products at the end of the blow down after the expansion phase of the cycle by fuel air mixture.
The present invention aims to overcome the disadvantages inherent to the conventional spark ignition engines, especially pertaining to high dilution, short circuiting and direct mixture loss.
SUMMARY OF THE INVENTION
The present invention provides an electronic continuous fueling device for an in-cylinder fuel injected spark ignition engine which negates the drawbacks of the conventional fueling devices.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides an electronic continual fueling device for use in spark ignition internal combustion engine. The fueling device of the present invention provides a solution to the problems related to short circuiting, dilution and direct mixture loss.
Solution to the problem of direct mixture loss requires that scavenging of the residual combustion products should be carried out with only air, and fuel should be introduced in the appropriate phase of the cycle separately. Through-put loss is mitigated to a substantial extent by in-cylinder injection during the open phase of the cycle and is completely eliminated if fueling is in the closed part of the cycle.
In two stroke spark ignition engines employing an in-cylinder injection, the fueling device is generally electro-mechanical. The fueling in such systems is cyclic while the quantity regulation with respect to operating conditions and timing are controlled electronically.
The present invention defines a fueling device designed to achieve in-cylinder injection in two stroke spark ignition engines where timing and cyclic nature of injection are taken care off by an air pump.
To mitigate the through-put loss, in-cylinder injection during the open phase of the cycle is carried out and to completely eliminate such loss fueling is carried out in the closed part of the cycle.
In-cylinder fueling necessarily involves meeting three related aspects-regulation of fuel quantity with respect to speed and load, disintegration of the metered quantity to the requisite degree of fineness to help rapid vaporisation of the fuel in the limited time available during compression, injection of the disintegrated fuel over the appropriate phase of the engine cycle and
dispersing it in the desired domain of the cylinder space.
The present invention describes a novel electronically controlled fueling device for an in-cylinder fuel injected spark ignition engine and it has been achieved in engines using fuel injectors with or without air assistance. In liquid fuel injection systems, high pressure is employed to achieve disintegration and dispersion of fuel. In air assisted systems, disintegration and dispersion is achieved by a relatively low pressure air blast. Low pressure in cylinder fuel injection system utilise air flow into the cylinder through the transfer passage for assisting disintegration and dispersion of the fuel air mixture.
The depression in the air pump provides the forcing function to the fueling device. The magnitude of the forcing function is appropriately attenuated and is made to act on a variable area fueling orifice. The fueling orifice is supplied with fuel under constant head as in a conventional fueling device.
The electronically controlled fueling device of the present invention is designed to meet throttle specific variable speed load fueling requirements of the engine and is simple, robust as well as cost effective.
The fueling device of the present invention is utilised for an efficient conversion of energy. The injection system including injection quantity and quality regulation is manipulated by the fueling device in accordance with the load requirements of an engine.
The passage and the dimensions of the fueling device of the present invention are critical and are engine specific.
The conventional fueling device is replaced by the electronically controlled fueling device where information is provided through a compact device comprising a valve and an electronic device. The said electronic device embodies the required information and controls the fuel injection performance as per the load requirements.
The fuel pump is connected to the valve of the said electronically controlled fueling device of the present invention which is controlled by the said electronic device. The said electronic device is connected to electromagnetic transducers. The opening and closing of throttle as per the requirements of fuel is communicated to the throttle transducer and the transducer outputs are further communicated to the said electronic device.
The fuel pump connected with the valve facilitates continuous injection. The valve ensures continuous and certain requisite rate of fuel flow, i.e., the valve controls and regulates the fuel flow rate. The valve is a simple tapered valve controlled electronically through a solenoid.
Therefore the said electronic device is a controlling valve in a manner that speed throttle stroke is detected and the required configuration is communicated through chip. The required configurations are dependent on the requirements of engine.
Accordingly the present invention relates to an improved internal combustion engine comprising a piston assembly in a cylindrical combustion chamber connected to a crank shaft having exhaust ports at its two ends; and fueling device connected to the said combustion chamber, wherein the said fueling device comprises a fuel pump and a valve connected thereon, said valve being controlled by electronically controlled means.
1. An improved internal combustion engine comprising a piston assembly in a
cylindrical combustion chamber connected to a crank shaft having exhaust ports at its
two ends; and fueling device connected to the said combustion chamber, wherein the
said fueling device comprises a fuel pump and a valve connected thereon, said valve
being controlled by electronically controlled means.
2. An improved internal combustion engine as claimed in claim 1, wherein the
said electronically controlled means is a microprocessor controlled chip.
3. An improved internal combustion engine substantially as herein before
|Indian Patent Application Number||833/DEL/1998|
|PG Journal Number||10/2008|
|Date of Filing||31-Mar-1998|
|Name of Patentee||DEPARTMENT OF SCIENCE & TECHNOLOGY, MINISTRY OF SCIENCE & TECHNOLOGY, GOVERNMENT OF INDIA|
|Applicant Address||TECHNOLOGY BHAVAN, NEW MEHRAULI ROAD, NEW DELHI 110016,INDIA|
|PCT International Classification Number||F02B 13/00|
|PCT International Application Number||N/A|
|PCT International Filing date|