Title of Invention

"AN IMPROVED PRESSURE-ACTUATING VALVE FOR 2-STROKE PETROL ENGINE"

Abstract

This Pressure Actuating Valve is devised to minimize escapement of unburnt charge from the exhaust port during scavenging action in 2- stroke engine. One reason for this problem is the higher location of exhaust port, compared to transfer ports. This valve closes the path, while rich charge is escaping through upper portion of exhaust port. This valve divides exhaust pipe in two compartments i.e. upper and lower. While lower compartment has direct access to exit, the upper compartment has this access through an opening in the valve body. This opening is closed and opened by a hinged flap valve actuating under gas pressure. A gripping mechanism controls the timing of valve. Exhaust gases disengage the grip and open the valve. The opened valve presents a large attack angle to exhaust flow, therefore gets again closed. When in closed position, it does not allow any gases which have gradually become a rich charge, to escape through upper compartment. This saved charge burns along with main charge, resulting in to enhancement in fuel efficiency and thrust of the engine.

Full Text

The present invention relates to a Pressure Actuating Valve for 2-Stroke petrol engine and is a new version in addition to the earlier version applied vide no. 65/Del/2000 dated.27th Jan. 2000. This new version is an improvement over the original version, where in the spring in the original version has been replaced with a new mechanism, thus enhancing its durability and efficiency. It is a known fact that 2-Stroke petrol engines suffer from a major disadvantage", that is, a large portion of unburnt charge or fuel-air mixture escapes through the exhaust port during scavenging action, as scavenging and charging actions take place simultaneously in 2-Stroke engines. This phenomenon is called short-circuiting of charge. This short-circuiting is the main contributory factor for low efficiency and higher emission levels in 2-Stroke engines Some measures are already in use to minimize the escapement of unburnt charge (short circuiting) through the exhaust port, such as crowning of piston top, or using deflectors, making angular direction of flow of fresh charge through transfer ports, in the opposite direction to the exhaust port, etc. But still a substantial quantity of unburnt charge escapes through the exhaust port, mainly due to its higher location in comparison to the location of intake or transfer ports, which is a necessary evil in 2-Stroke engines as set out below. The higher location of exhaust port in comparison to the intake or transfer ports has two divergent effects. One of which is highly desirable and the other is equally undesirable i.e. during the piston journey from Top Dead Centre (TDC) to Bottom Dead Centre (BDC), it is most desirable to open the exhaust port first so that the burnt gases at high pressure may be allowed to escape and the pressure in the cylinder brought down, so that the fresh charge of fuel-air mixture is able to enter into the cylinder through the transfer ports. This desirable feature can be achieved only when the exhaust port is opened first. Therefore exhaust port is located at a higher location in comparison to the transfer ports. On the other hand it causes the exhaust port to close late in comparison to the transfer ports during the return journey of the piston i.e. from Bottom Dead Centre (BDC) to Top Dead Centre (TDC). This is equally an undesirable feature, because, both, the exhaust port and transfer ports are open and scavenging and charging actions take place simultaneously. The charge in the cylinder is gradually getting rich and till the exhaust port gets closed, the said short circuiting continues to take place. But considering a stage when transfer ports have just closed but the exhaust port is yet to be closed, only the fully concentrated or rich charge is escaping through the exhaust port, because by then the charge in the cylinder attains full rich ness, to the extent possible. This escapement of fully rich charge continues till the exhaust port gets closed. Evidently, short-circuiting during the above stage is particularly harm full because of high richness of charge. This stage contributes largely to the total short-circuiting of charge. Although short-circuiting begins to take place much earlier to this stage, it starts to become particularly harm full, little before and during the course of the above mentioned stage, because of high richness of charge. This valve is particularly designed to prevent said short-circuiting when charge in the cylinder gets sufficiently rich or concentrated. It is an object of this invention to provide a Pressure Actuating Valve for 2-Stroke petrol engine which significantly reduces the escapement of unburnt charge from the exhaust port, due to short circuiting, a problem associated with 2-Stroke engines and is much more intense in the prior structures of this general type. It is a further object of this invention to provide a Pressure Actuating Valve for 2-Stroke petrol engine, which effectively improves volumetric efficiency, fuel efficiency and thrust of the engine and reduces emission levels, particularly hydrocarbons in the exhaust gases of 2-Stroke engine. It is a further object of this invention to improve upon the earlier version of Pressure Actuating Valve and making it more efficient and durable, where in the spring in the earlier version has been replaced with a new mechanism. Further and additional objects will become apparent from the description/accompanying drawings and appended claims. In accordance with one embodiment of the invention, a Pressure-Actuating Valve for 2-Stroke engine has been provided, which comprises a trapezoid like shaped valve body being fitted in the exhaust pipe of the engine, dividing the exhaust pipe in two compartments, upper compartment and lower compartment, the said upper compartment being tightly enclosed from 3 sides and 4th side opening in the cylinder; the said three sides being defined by 2 longer sides of the said trapezoid like shaped valve body, flushing with the exhaust pipe internal walls and an arc shaped washer at one end of the valve body, in conjunction of which the valve body is clamped and screwed with the wall of the exhaust pipe, through an oblong hole in the said end of the valve body, the other end of the valve body opening in the cylinder and having a shape of concave curve, the said concave curve, resting in line with the curve of cylinder bore and staying close but just clear of the running piston, the said lower compartment having direct connectivity from cylinder to the exit via exhaust pipe and all the gas flow from the said upper compartment to the said lower compartment taking place through an opening in the valve body, which is getting closed and opened by a hinged flap valve, actuating under the pressure of cylinder gases and who's timing being controlled by a gripping mechanism, consisting of an engaging plate, engaging lever, hinge pin and servo arm. Now this invention is described with reference to accompanying drawings, in accordance with one embodiment of the present invention. Figurel (sheet 1), is a top plan view of the Pressure Actuating Valve and shows valve body, rectangular shaped opening, oblong hole, concave curve, longer sides of the valve body, hinge pin, gripping mechanism, pivot of the gripping mechanism, engaging plate and guide wire or edge. Figure2 (sheet 1), is a side view of the Pressure Actuating Valve and shows, flap valve, hinge, two supporting webs, servo foil, engaging lever, nut, bolt, arc shaped washer, hole in the exhaust pipe and exhaust pipe wall, in cross section. Figure3 (sheet 1), is a front view of the Pressure Actuating Valve and shows servo arm Fig.4(sheet 2), shows the cross sectional view of a conventional cylinder block of a 2- stroke engine, with Pressure Actuating Valve, fitted in the exhaust pipe of the cylinder block, showing, exhaust pipe, upper compartment, lower compartment, piston, cylinder, exhaust port, transfer ports and cylinder gases The following indicate in the drawings what is set out against each number. - (A) Parts relating to the Pressure Actuating Valve i Valve body 1a Rectangular opening in the Valve body 1b Narrower end of the Valve body having an Oblong hole 1 c Concave curve at the broader end of Valve body 1d Longer sides of the Valve body 2 Arc shaped washer 3 flap valve 4 Hinge pin for hinging the flap valve with the Valve body 4a Hinge on the flap valve 5 Supporting web, on the valve body, for its proper positioning and strengthening 6 engaging plate, a component of gripping mechanism 7 Supporting web, on the flap valve for its strengthening 7a Servo foil, on the tip of the supporting web 8 Guide wire or edge, a component of gripping mechanism 9 Gripping mechanism 9a Pivot of the gripping mechanism 9b Engaging lever of the gripping mechanism 9c Servo arm of the gripping mechanism 10 Nut for clamping the valve body 11 Bolt for clamping the valve body (B) Parts relating to conventional cylinder block of a 2- stroke engine, where Pressure Actuating Valve is being fitted: - 12 Hole in the exhaust pipe wall 12a Exhaust pipe wall in cross section 13 Exhaust pipe 14 Upper compartment 15 Lower compartment 16 Piston 17 Cylinder 18 Exhaust port 19 Transfer port 20 Cylinder gases Referring to Fig. 1-4 (sheet 1-2) of one form of Pressure Actuating Valve, which is generally made of alloy steel, the valve body (1) is a base plate having a trapezoid like shape such that when fitted in the exhaust pipe (13), its longer sides (1d) make a close fit and flush with the internal walls of the exhaust pipe (13) and the concave curve (1c) on its one (broader) end rests inline or coincides with the curved surface of cylinder bore(17), leaving some clearance with the running piston (16) for taking care of linear expansion of the valve body (1), due to heat. The relative position of the valve body (1), at the mouth of the exhaust port (18) is such, that the height of the concave curve (1c), from the lower surface of the exhaust port (18) is not less than 50% and not more than (75%) of the total height of the exhaust port (18). Valve body (1) has one rectangular shaped opening (1a) in its middle portion (This opening could be of semi oval or other like shaped), for transfer of gases (20). Valve body (1 )also has an oblong hole(1b), at the other (narrower) end and is used to position and clamp the valve body (1) to the exhaust pipe wall (12a) with the help of nut(10) and bolt (11) in conjunction with an arc shaped washer (2), whose arc diameter is equal to the bore diameter of the exhaust pipe and arc thickness is not less than15% and not more than 25% of bore diameter of the exhaust pipe (depending upon the design requirements). This arc shaped washer (2) ensures closing and sealing of the narrower end (1b) of the valve body (1) from the gap between it and the exhaust pipe wall (12a), thus leaving only the rectangular shaped opening (1a) for transfer of gases, after the Pressure Actuating Valve is fitted and clamped in the exhaust pipe (13). (This arc shaped washer(2) could be integral to the valve body 1). To accommodate arc shaped washer (2) and ensure close fitting with the exhaust pipe (13) walls, the said narrower end (1b) has been given a slight bend. The said clamping is done through a drilled hole(12), situated at a predetermined point in the exhaust pipe wall (12a), towards Top Dead Centre This point is determined by the distance from the centre of the concave curve (1c) at one end of the valve body (1) to the centre of the oblong hole(1b) at the other end of the valve body (1), which is not less than 140% and not more than 200% of the exhaust pipe (13) bore diameter, (depending upon the design tequirements). To ensure its positioning firmly and avoid springing action while in operation a supporting web (5), at right angle is provided at the centre of broader end, having concave curve (1c), whose edge rests on the lower surface of the exhaust pipe (13), for support. A vital part of this Pressure Actuating Valve is a thin rectangular metallic plate, similar in shape, but little over size than to the rectangular opening, which carries a hinge (4a) on its one end and acts as a flap valve (3). To give strength to this flap valve (3), a supporting web (7), is provided at the centre line of its entire length, at right angle. This supporting web (7) in turn carries a servo foil (7a) on its tip which presents a small surface area in between 3% to 5% of the exhaust port (18) area, for giving additional force in closing the flap valve (3). This is to be understood that the flap valve (3), supporting web (7) and servo foil (7a), all the three are at right angle to each other. An engaging plate (6) is also disposed on the centre line of the flap valve (3) at right angle to it, just opposite to the supporting web (7). The edge of the engaging plate (6) has a shape of convex curve with a groove cut at the bottom of the curve. This engage plate (6) is positioned on the flap valve (3) at the opposite end to the hinged end, but at right angle to it. This flap valve (3), is disposed on the valve body (1) with the help of a hinge pin (4). The hinge pin (4) passing through the hinge (4a) of the flap valve (3) and its ends fixed with the valve body (1),such that the hinge pin (4) is positioned on the edge of the rectangular opening (1a), which is towards concave curve (1c) of the valve body (1).Thus making flap valve (3), oscillate on the hinge, in such a way that when in closed or up position it covers/ shuts the rectangular opening (1a) completely and when in down position it uncovers/ opens the rectangular opening (1a). In order to make this flap valve (3) to operate at desired timing, a gripping mechanism (9), consisting of a pivot (9a), an engaging lever (9b), a servo arm (9c) and a guide wire or edge (8), is disposed on the valve body (1), in addition to the above said engaging plate (6), which is disposed on flap valve (3). The said gripping mechanism (9) is so designed that it has a pivot (9a) passing through a pivot hole (which acts as a pivot point) across the thickness of the valve body (1). One end of the pivot (9a) opens towards the upper side (side towards Top Dead Centre after fitting) of the valve body (1) and the other end of the pivot (9a) opens towards the lower side of the valve body (1). The said pivot hole is positioned adjacent to the supporting web (5) on the valve body (1), keeping small distance of 3 to 5mm from the concave curve (1c) of the valve body (1). On the upper side of the valve body (1) the pivot (9a) carries an engaging lever (9b), which is given V like shape bend. The bent arm of the lever (9b) is extended up to the engaging plate (6) and some portion of it is kept protruding beyond the engage plate (6), for presenting a small front area to the exhaust flow. While the flap valve (3) is in close position and engaging lever (9b) is in engaged position, this extended arm of the engaging lever (9b) rests in the groove of the engage plate (6) and keeps the flap valve (3) gripped in that position. The protruding portion of the engaging lever (9b), though having a very small front area, is capable of producing a couple force around pivot point (9a) under the high pressure of exhaust gases (20), such that it is capable of pushing away the engaging lever (9b) from the groove of the engage plate (6), to bring it to the disengaged position. In this position, the flap valve (3) gets open by the same exhaust pressure. On the lower side of the valve body (1), the other end of the pivot (9a), carries a servo arm (9c), extending towards the edge of the valve body (1), with a comparatively larger front area, at its end, than to the protruding arm of the engaging lever (9b) and is not less than 3% and not more than 5% of the exhaust port area. The said servo arm (9c) produces a larger couple force under the low pressure of gases (20) in opposite direction to the one produced by the protruding arm of the engaging lever (9b), such that, it is capable of pushing away the servo arm (9c), below and pulling in the engaging lever (9b), above the valve body (1), to its engaged position in the cut groove of the engage plate (6), after the flap valve (3) has come to closed position. To control the movement and make the engaging lever (9b) move in a plane, a guide wire or edge (8), keeping a uniform gap from the valve body (1), is provided above the protruding arm of the engaging lever (9b), for its smooth reciprocating movement in the gap and also to ensure that the engaging lever (9b) does not overjump the convex curve of the engaging plate (6), and get stuck during operation. This Pressure Actuating Valve, after fitting in the exhaust pipe (13), divides the exhaust pipe in two compartments i.e. upper compartment (14) (towards Top Dead Centre) and lower compartment (15) (towards Bottom Dead Centre ). The upper compartment (14) is thus completely closed and sealed from exit, due to close fitting of the two longer sides (1d) of the valve body (1) with the walls of the exhaust pipe (13) and the arc shaped washer (2) on its narrower end (1b). At the broader end side, which is having concave curve (1c), both the compartments are opening in the cylinder and getting closed and opened by the movement of the piston (16). In this position, while the lower compartment (15) has the direct connectivity for gases to pass to exit, the upper compartment (14) has this connectivity to exit via rectangular opening (1a). Therefore any escapement of gases (20) from upper compartment (14) have to be through the rectangular opening (1a), which is getting opened and closed by the hinged flap valve (3). This hinged flap valve (3) in turn actuates according to the direction of pressure acting on it and its timing controlled by the gripping mechanism (9). The operation of this valve is based upon the phenomena that the pressure of the gases (20), while the piston(16) is descending from Top Dead Centre (TDC) to Bottom Dead Centre (BDC), is much higher than while it is ascending from Bottom Dead Centre (BDC) to Top Dead Centre (TDC). The above pressure difference has been put to advantage to operate the valve in such a fashion that the high pressure of burnt gases, while the piston(16) is descending through the upper compartment (14), force opens the flap valve (3) by disengaging the engaging lever (9b) from the groove of the engaging plate (6) due to the couple force produced by the high pressure gases (20), on the arm of the engaging lever (9b). This opened flap valve (3) gives way to the gases (20) to pass from upper compartment(14) to lower compartment (15) through the rectangular opening (1a). Since the lower compartment (15) has direct connectivity to the exit through exhaust pipe (13), the gases (20) eventually pass to the exit through it. With the further travel of the piston(16) downwards and its reaching the lower compartment (15), the reduced pressure which is still quite high, now acts on the other side also or from beneath the valve body (1). In this position, flap valves (3), presents a large attack angle to the gas flow and is forced to close. Simultaneously, the reduced gas pressure acts on the servo arm (9c), which produces a couple force in the opposite direction than to the one produced by the engaging lever (9b) above and pushes the servo arm (9c) away there by engaging lever (9b) gets pulled and engaged in the groove of the engaging plate (6). Hence, immediately after closing, the flap valve (3) stands gripped by the gripping mechanism (9). To give more thrust for closing, a servo foil (7a) is provided to the flap valve, which presents small surface area which is not less than 3% and not more than 5% of the area of the exhaust port (18), at right angle to the gas flow. Rebound force of the supporting web (7) from the surface of the exhaust pipe (13) also gives added force for closing the flap valve (3) After the flap valve (3) has come to closed position, there is no escapement of gases (20) through the upper compartment (14). During further downward and upward journey of the piston (16), the low pressure of gases (20) is not able to disengage the engaging lever (9b). Therefore flap valve (3) remains closed and all the escapement of gases take place through the lower compartment (15) only. Consequently all the escapement of gases stops after the piston has covered the lower compartment(15) during its upward journey towards Top Dead Centre (TDC). Hence the area of upper compartment (14), which was exposed to the exit in the earlier structures of prior art has been timely closed as set out above and does not allow any gases (20), (which by now have become fully rich mixture), to escape. The net result is that the undesirable phenomena i.e. the escapement of unburnt mixture due to the higher location of the exhaust port in comparison to the transfer ports has been taken care of by this valve by not allowing the gases to pass to the exit through its upper compartment (14) It is this saving of rich mixture and making it to burn along with the main charge that benefits the overall performance of the engine as well as contributes in lowering the emission levels particularly hydro carbons and enhancing its thrust, volumetric efficiency and fuel efficiency. While a specific embodiment has been illustrated and described, it is to be understood that the relative positions of the components, dimensions and shapes may vary as the size of the engine or other design requirements necessitate. Accordingly, variation modifications and substitution of equivalent mechanism can be effected within the scope of this invention. We claim: A Pressure-Actuating Valve for 2-Stroke engine, comprising a trapezoid like shaped valve body (1) being fitted in the exhaust pipe (13) of the engine, dividing the said exhaust pipe (13) in two compartments, upper compartment (!4) and lower compartment (15), the said upper compartment (14) being tightly enclosed from 3 sides and 4th side opening in the cylinder (17); the said three sides being defined by 2 longer sides (1d) of the said trapezoid like shaped valve body (1), flushing with the exhaust pipe (13) internal walls and an arc shaped washer (2) at one end of the valve body (1), in conjunction of which the valve body (1) is clamped and screwed with the wall of the exhaust pipe (13), through an oblong hole (1b) in the said end of the valve body (1), the other end of the valve body (1) opening in the cylinder (17) and having a shape of concave curve (1c), the said concave curve, resting in line with the curve of cylinder bore and staying close but just clear of the running piston (16), the said lower compartment (15) having direct connectivity from cylinder (17) to the exit via exhaust pipe (13) and all the gas flow from the said upper compartment (14) to the said lower compartment (15) taking place through an opening (1a) in the valve body (1), which is getting closed and opened by a hinged flap valve (3), actuating under the pressure of cylinder gases and who's timing being controlled by a gripping mechanism (9), consisting of an engaging plate (6), engaging lever (9b), pivot (9a) and servo arm (9c). 1 A Pressure-Actuating Valve as in claim 1, where in the said Pressure Actuating Valve is fitted in the exhaust pipe (13) of 2-Stroke engine in the manner that the relative position of the said concave curve (1c) at one end of the said valve body (1), at the mouth of the exhaust port (18) being such, that the height of the said end having concave curve (1c), from the lower surface of the exhaust port (18) is not less than 50% and not more than 75% of the total height of the exhaust port (18) and the said valve body (1) being clamped and screwed with the exhaust pipe(13) wall through the said oblong hole (1b), at the other end of the valve body (1), in conjunction with an arc shaped washer (2), who's arc diameter is equal to the bore diameter of the exhaust pipe (13) and arc thickness is not less than 15% and not more than 25% of bore diameter of the exhaust pipe and the said clamping is done through a drilled hole at a predetermined point in the said exhaust pipe (13) wall, towards Top Dead Centre, location of which is such that, on fitting, its distance from the centre of the concave curve (1c) at one end of the valve body (1), is not. less than 140% and not more than 200% of the exhaust pipe (13) bore diameter. 2 A Pressure-Actuating Valve as in claim 1, where in the said hinged flap valve (3) alternately shuts and opens the said opening (1a) in the valve body (1) and actuates under the influence of gas pressure in the cylinder (17), acting on its surface as well as on the servo foil (7a) disposed on the flap valve (3). 4 A Pressure Actuating Valve as in claim 1, where in the said gripping mechanism (9) is employed for operation of the said hinged flap valve (3) at desired timing and where in the arm of the said engaging lever (9b) engages and disengages alternately from the groove of the said engaging plate (6) due to the couple forces produced alternately in the opposite direction to each other, by the protruding arm of the said engaging lever (9b) above and the said servo arm (9c) below the said valve body (1) under the influence of gas pressure. 5 A Pressure-Actuating Valve for 2-stroke petrol engine (addition), substantially as herein described with reference to the figures 1,2,3&4 of the accompanying drawings.

Documents:

680-del-2002-abstract.pdf

680-del-2002-claims.pdf

680-del-2002-complete specification (granded).pdf

680-del-2002-correspondence-others.pdf

680-del-2002-correspondence-po.pdf

680-del-2002-description (complete).pdf

680-del-2002-drawings.pdf

680-del-2002-form-1.pdf

680-del-2002-form-13.pdf

680-del-2002-form-19.pdf

680-del-2002-form-2.pdf

680-del-2002-form-3.pdf