|Title of Invention||
AN IMPROVED FUELLING DEVICE FOR AN INTERNAL COMBUSTION ENGINE
|Abstract||An improved fueling device for an internal combustion engine compromising: a rectangular container having means to maintain constant level of fuel; hollow cylindrical chamber provided on the said container having an integrated piston moving up and down in the said cylindrical body; a controller connected to the said cylindrical chamber having means for regulating the movement of said piston within the said cylindrical chamber; wherein the said cylindrical chamber has a fixed size orifice as herein described having a tapered needle configuration with an integrated piston feature, moving up and down through the controlling means.|
|Full Text||The present invention relates to an improved fueling device for an internal
Combustion engines. The main embodiment of the present invention resides in the continual fueling capacity of the fueling device.
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 a fueling device for an in-cylinder fuel injected spark
ignition engine which negates the drawbacks of the conventional fueling devices, i.e.,
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a 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 of 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 fueling device for an in-cylinder fuel injected spark ignition engine. The 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 extreme mechanical design simplicity and the low cost thereof are the principal advantages of the mixture scavenged spark ignition engine incorporating the fueling device of the present invention.
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 fueling device for an in-cylinder fuel injected spark ignition is devised for use 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.
In air assisted systems, 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 fueling device of the present invention has four parts, container, chamber, connector and controller. The container has a means to maintain a constant level of fuel. These means are float level indicator which helps maintaining constant level of fuel. The chamber is a cylindrical chamber having a fixed size orifice in which a tapered needle with an integrated piston feature is moved up or down by the controller
operating through a cable. Controller also possesses a facility to sit the needle at the desired position to achieve the required idling speed. The inlet to the fueling devices is connected to an air pump. 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 in a variable area fueling orifice.
The tapering of the needle provides charged annulus area where the extent of tapering is decided by the quantity (maximum and minimum) in which fuel is required. The fueling device of the present invention provides that a predetermined quantity of fuel is provided to the engine.
The fueling device of the present invention is provided with variable area needle valve to regulate speed load varying requirements. It has an integrated pumping feature to meet the starting fuel requirements and acceleration/deceleration transient fuel requirements. The dimensions of air flow passages are based on low air flow in the air pump injection system.
The integrated pump feature meets the starting acceleration/deceleration fueling requirements. The tapered part of the needle is designed to meet the variable speed load fueling requirements.
The pump employed in the fueling device is a simple reciprocating pump operated whenever throttle is opened or closed, i.e., it opens and closes as per the requirements of fuel by the engine.
The present invention is precisely described with reference to the accompanying drawings. The drawings as presented are for illustrative purposes only and do not restrict the broad scope of the invention wherein:
Figure 1 end 2-show the fueling device of the present invention.
Figure 1 shows four parts of the fueling device of the present invention, i.e., the container, chamber, connector and the controller. The container of the present invention comprises means for controlling level of fuel in the fueling device. These
means are basically a float level indicator. The cylindrical chamber of the present invention is having a fixed size orifice in which a tapered needle with an integrated piston is moved up or down by the controller operated through a cable. Connector is the end which connects fueling device with engine. The controller comprises an
accelerator cable(1) for controlling the movement of piston which is regulated using a
reciprocating pump. The pump is operated whenever throttle is opened or closed.
Figure 1 shows the fueling device comprising of an inlet chamber also working as an air filter (9), a control element (10) and the fuel control needle (11) working in the fueling chamber (12). The fuel control needle (11) has special features for starting/acceleration, i.e. (13), high speed operation (14), low speed operation (15) and idling(16). These special features are in the form of tapering of the fuel control needle which provides charged annulus area where the extent of tapering is decided by the quantity of fuel required to be injected in the engine. The quantity of fuel required to be injected is in turn dependent on the load features of the engine. The fueling chamber is connected to the inlet of the air pump.
Thus the present invention relates to a continuous fueling device for in cylinder fuel injected spark ignition engines.
1. An improved fueling device for an internal combustion engine comprising:
a rectangular container having means to maintain constant level of fuel;
hollow cylindrical chamber (12) provided on the said container having an integrated piston (11) moving up and down in the said cylindrical body;
a controller as hereindescribed connected to the said cylindrical chamber having means for regulating the movement of said piston within the said cylindrical chamber;
wherein the said cylindrical chamber has a fixed size orifice as herein described having a tapered needle configuration (13, 14, 15, 16) with an integrated piston feature, moving up and down through the controlling means.
2. An improved fueling device as claimed in claim 1, wherein the said means for
maintaining constant level of fuel in the said rectangular container is a float level indicator.
3. An improved fueling device as claimed in claim 1, wherein the said means for
regulating movement of said piston within the said cylindrical chamber is an accelerator
cable for controlling the movement of the said piston.
4. An improved fueling device as claimed in claim 1, wherein the said piston movement
is regulated using a reciprocating pump and is operated whenever throttle is opened or
5. An improved fueling device, substantially as herein before described with reference to the accompanying drawing.
|Indian Patent Application Number||834/DEL/1998|
|PG Journal Number||01/2009|
|Date of Filing||31-Mar-1998|
|Name of Patentee||DEPARTMENT OF SCIENCE OF TECHNOLOGY|
|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|