US2023048A - Internal combustion engine - Google Patents

Description

2 Sheets- Sheet 1 Dec. 3, 1935. M. GENTlLl INTERNAL COMBUSTION ENGINE Filed July 27, 1952 o 9 b 7 m 4 a we a 2 0 0 F 7 2 3 0 Z 4 2 3 W G O 9 W 3 WW ,4 5 E u w a 0 "a" n 2, MN 2 x a W. 4 2. z 7 2 2 d 93 33 x 3 r/ Y 2 E w v 4 /0 MW A. 3 v \S S we 2 H E 7 H 4 4 .0 6 I E: J r J 1 1 a M M 2 Sheets-Sheet 2 H H w M 8 A. 7 J 5 M W. ww w a 5% w I z Il N: J LO fi a w n 6 .m, w JM W\ 5 I. W w 3mm 1v g H 2 5 a .r 7 w 7 a m M n M Dec. 3, 1935. M. GENTILI INTERNAL COMBUSTION ENGINE Filed July 27, 1952 Patented Dec. 3, 1935 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates particularly to that type of internal combustion engines known as twocycle engines. The invention relates more particularly to the means for reducing the pressure in the cylinders thereof when the engine is idling or running at a reduced power; to means for controlling such pressure reduction; to means for supplying the fuel mixture to such engine; to means for controlling such fuel supply; and to means for coordinating the two said controlling means.

The object of the invention are to provide improved mechanism for controlling the compression pressure of the engine; for operating the pressure meter valve; for controlling the time for opening and closing said meter release valve, and for controlling the degree of such opening; for operating the fuel supply valve; for controlling the time for the opening of said fuel supply valve, and the degree of such opening; and for coordinating the action of said two time controlling means. A further object is to provide a cheap, simple and effective mechanism, easily inspected, adjusted and repaired, and which is thoroughly rugged and practical, whereby the two-cycle engine may be made more elastic in its operating conditions and whereby its many advantages may be made effective.

I attain these and other objects by the devices,

mechanisms, and arrangements illustrated in the accompanying drawings, in which- Fig. 1 is a vertical section of an engine made in accordance with my invention; Fig. 2 is a vertical section of a part thereof through the metering mechanism, drawn to a larger scale and showing the parts in the positions occupied thereby when the piston is at the lower end of its stroke and showing the adjustment of the control mechanism for full power or high speed; Fig. 3 is a similar view showing the parts adjusted for low power or idling speed; Fig. 4 is a vertical section of a part thereof through the fuel feed mechanism, showing the parts in the positions occupied thereby when the piston is at the lower end of its stroke, and showing the adjustment of the control mechanism for full power and high speed; Fig. 5 is a similar view showing the parts in the positions occupied thereby when the piston is approaching the upper end of its 50 travel, at a point immediately preceding the cutting off of its fuel supply, and showing the adjustment of the control mechanism for low power or idling speed; Fig. 6-is a horizontal section of a single cylinder of such an engine, taken on the lines 5-6 in Figs. 2 and 4; and Fig. 7 is a diagrammatic view of the fuel and combustion air supply means.

Similar numerals of reference refer to similar parts throughout the several views.

The engine comprises the usual construction 5 of a cylinder I, or series of such cylinders, having a head 2, and surrounded by a suitable cooling means, such as the water-jacket 3. The head is provided with a combustion chamber 4 and with a suitable spark plug 5. A piston 6 recipl0 rocates in the cylinder I in the usual manner, and is connected to the crank I of the engine shaft 8 by the usual connecting rod 9. The shaft 8 drives the cam shaft l0, through the equal gears ll, indicated in dotted lines in Fig. 1, at the 15 same rate of rotation.

The cylinder I is provided with an exhaust port I2 adjacent to the lower end of the stroke of the piston 6, and with a scavenger port l3 opposite thereto. The upper wall of the exhaust port I2 20 is slightly higher than the upper wall of the scavenger port l3, thus permitting the pressure in the cylinder to be lowered through the exhaust before the scavenger port is opened. The scavenger port it is connected by suitable passage 25 to the scavenger chamber M, which is supplied with air under pressure from the scavenger manifold l5. The air in the scavenger manifold I5 may be supplied by any convenient means, not

shown, and should have a pressure of from 5 30 to 25 lbs. per square inch, the higher the pressure the more rapid the action.

The upper surface of the piston 6 is shaped to have a downward inclined face it from a raised central ridge H and leading to the exhaust port 35 when the piston is at the lower end of its stroke, and a concave curved portion is leading from the said ridge l! to the scavenger port is when the piston is in said same position, thus directing the scavenger air from the port. l3 up towards the combustion chamber 4 and reversing permitting the burnt gases to pass out of the exhaust port it freely and easily.

Referring now to Figs. 2 and 3, it will be seen that I provide an air port it. This port It! is positioned with its center about one-quarter of the piston stroke down from the upper end thereof. The port l9 leads to a valve chamber 20. A meter valve 2i opens into the valve chamber 20 to open connection with the air passage 22. A three-way valve 23 is mounted in this passage 22, to permit air to pass out of the open port 2% or to be returned to the scavenger chamber I 4 by the return by-pass pipe 25.

The valve 2! is operated by the following mechanismz-Th camshaft I is provided with a suitably shaped cam 26 which raises a plunger 21 against the action of the spring 23. The plunger 2'! is suitably mounted in the engine frame and is adapted to be reciprocated therein. A rod 29 is secured to the upper end of the plunger 2! and is provided with an operating wedgeshaped head 30 at its upper end. The valve 2| has a stem 3| extending out from the engine and this stem 3| isengaged by a spring 32 which always tends to close the valve 2| tightly on its seat, to close connection between the valve chamber 20 and the air passage 22. A control shaft 33 is mounted adjacent the cylinder head 2, parallel with the engine shaft 3, and operated by any suitable means but preferably by means of a foot lever controlled and actuated by the operator of the engine. This shaft 33 has an air control cam 34 thereon. This cam 34 operates a rocker lever 35, suitably mounted on a bracket 36, against the action of the spring 31. The contact between the cam 34 and the lever 35 may be adjusted by the contact set screw 33. The other end 39 of the lever 35 extends down to a point substantially in the extension of the axis of the valve stem 3| but removed therefrom and forms a back-stop for the head 30 above described. When the engine operator wishes the engine to idle, he turns the shaft 33 to bring the cam into the position shown in Fig. 3. In this position the cam 34 is furthest extended from the axis of the shaft 33 at its point of contact with the adjusting screw 38 of the lever 35, thus swinging the said lever 35 to its greatest extent, against the action of the spring 31, and bringing the backstop 39 thereof closest to the valve stem 3|. The head 39 of the rod 29 is positioned between the said back-stop 39 of the control rocker lever 35 and the outer end of the valve stem 3|. A swinging roller 40 may be hung from the bracket 36 and positioned between the head 30 and the stem 3|. When the piston 6 is close to the lower end of its stroke, the cam 26 begins to rise and push the plunger 21 (Fig. 3) which forces the wedgeshaped head 30 upward between the adjustable back-stop 39 and the valve stem 3| and therefore begins to open the valve 2|. The further rotation of the shaft 0 therefore opens the valve 2| to its full extent and holds it open while the piston 6 is rising. As the piston 6 rises it drives out part of the clean air in the cylinder through the port I9, chamber 20, and passage 22, so long as the valve 2| remains open, thus preventing any compression of the air in the cylinder until the said valve 2| has been closed. With a further rising of the piston 6 and corresponding rotation of the shaft l0, the cam 26 recedes from the plunger 21, which follows it down under the action of the spring 26, thus withdrawing the wedge-shaped head '30 from between the backstop 39 and the roller 40 or the end of the stem 3|, thus permitting the spring 32 to return the valve 2| to its seat and thus close the passage 22. Compression of the remaining air in the cylinder begins at this point. The extreme moment when this valve 2| is thus closed is preferred to be such that the piston 6 will have traveled about three-fourths of its stroke upward.

When the engine operator causes the control shaft 33 to be rotated from the above-described position, of idling speed or low power, the backstop 39 is moved further outward thus increasing the gap between it and the roller 40 or the valve stem 3|, with the result that the wedge head 30 will rise further before it forces the valve 2| open, as above described, and therefore the valve 2| will remain closed longer and will close sooner than when the engine is idling (Fig. 3) and also, since the said space is increased, the extent that the valve 2| will be thus opened will be equally decreased. When the engine operator turns the shaft 33 into the extreme high speed position (Fig. 2) the valve 2| remains closed, or opens momentarily a very minute amount, and the engine compression, power and speed are therefore increased to the fullest extent, especially since the supply of fuel is correspondingly increased, as hereinafter described.

Referring now to Figs. 4 to 7, it is seen that a fuel port 4| is positioned in the cylinder at a point slightly above that of the meter port l9 (Fig. 2) and to one side thereof (Fig. 6) ,-at a position with respect to piston movement to be covered by that member during the firing period. The outer portion of. the port passage is somewhat enlarged and is provided with the fuel supply fitting 42 secured therein. The fitting 42 is provided with an air supply passage and pipe 43 and a fuel supply passage and pipe 44 (Fig. 6) leading to the seat of the needle valve 45, and with an outlet passage 46 leading therefrom. A spray nozzle 41 is mounted in the end of the outlet passage 46 and extends to the port 4|. The fitting 42 also has a cylindrical chamber 49 terminating in the needle valve seat. The needle valve 45 has a stem 49 extending out beyond the fitting 42.

A flexible airtight gasket 50 is secured to the stem 49 of the needle valve 45, immediately at the rear thereof, and is held in the cylinder 48 by means of the tubular holder 5|, fitting tightly in the chamher 48 and held therein by the head 52 which closes the chamber 48. A spring 53 is mounted around the stem '49, between the needle valve and the head 52, and presses the said needle valve on to its seat to close the passages 43 and 44. The 40 stem 49 is provided with a vertical slot 54 near its outer end, outside of the fitting 42.

The cam shaft I0 is also provided with a fuelsupply-operating cam 55. This cam is shaped to rise gradually from the shaft and, having at- 46 tained its maximum height, to return sharply thereto again, as shown in Figs. 4 and 5. The cam 55 engages a roller 56, mounted on the plunger 51, to raise the said plunger against the action of the spring 58. An operating rod 59 is attached to the plunger 5'! and extends upward therefrom. The rod 59 is provided with a wedge or inclined surface 60, on its outward side, adjacent its upper end. The upper end of the rod 59 passes through the slot 54 in the stem 49 of the needle valve. The fuel fitting 42 carries a bracket 6| which has an arm 62 extending therefrom, said arm 62 being adapted to form a fixed back-stop for the inner surface of the rod 59. The abovedescribed control shaft 33 carries a fuel control cam 63. A rocker lever 64 is mounted on the bracket 6| and is provided with an adjustable contact screw 65 engaging the said cam 63. A spring 66 tends to hold the screw 65 in contact with the cam 63. The outer end of the lever 65 64 carries a swinging link 61 which is provided with a suitable roller 66 at its end. The roller 68 is positioned in the slot 54 of the stem 49 of the needle valve and'adjacent the outer side of the rod 59, and is adapted to engage the wedge 60 when the rod 59 is raised. Thus it will be seen that when the rod 69 is raised by the cam 55 to drive the wedge 60 upward it will force the roller 63 against the end of the slot 54 and thus will force the stem 49 outward and will withdraw the 7 needle valve 45 from the ends of the passages 48 and M, thus admitting air and fuel to the conically annular space surrounding the needle valve: and that such air and fuel will then mix and the fuel will be atomized and will pass into the cylinder I! through the passage 46, nozzle 41 and port M.

'Ihe fuel control cam 83 is in substantially the opposite phase from the meter cam 34 but both are mounted on, or formed on, the same controlled shaft 33. The operating cam 55 and the inclined surface as are so proportioned and positioned that the needle valve 45 will close quickly when the piston is between one-sixth and oneeighth of its stroke from the top, independent of the adjusted position of the control cam I.

When the operator wishes to drive the engine at full power and speed, he turns the shaft 38 so that the cam 53 will raise the end of the lever 84 (Fig. 4), thus depressing the roller 68 and causing it to contact with the inclined surface at an earlier moment, thus opening the valve 45 sooner, and also to a greater degree, than when the shaft 33 is turned to any other degree, and thus increas-- ing the quantity of fuel vapor admitted into the cylinder i. At this position of greatest power and speed, the valve 45 opens when the piston 8 has closed the exhaust port i 2.

As the control shaft 53 is turned away from its maximum speed position, the roller 68 is raised slightly with the result that the valve 45 opens later and in lesser degree. The cams 28 and 55 on the operating cam shaft ill, the cams 34 and 63 on the control cam shaft 33, and the shape of the wedge surfaces 30 and 60 are so proportioned and shaped that the fuel supply needle valve 45 will not be opened until the meter valve 2i is closed, thus preventing the wastage of the fuel.

An air pump, indicated diagrammatically at 89 in Fig. 7, is operated by suitable means and supplies the proper volume of air for the vaporization of the fuel, at a pressure of from ten to forty pounds per square inch. The air is conducted from the pump 69 by the pipe 10 to the upper part of the container ll whence it is conducted by the air pipe 43 to the needle valve 45. Also a fuel pump 12 is operated by suitable means and pumps the proper volume of liquid fuel from a supply tank (not shown) by the suction pipe 13 and delivers it by the pipe I4 to the lower part of the same container 1 l, whence it is conducted by the fuel pipe 44 to the needle valve 45. The amount of fuel in the container H is controlled by the float I5 and needle valve 16. A spring controlled by-pass valve 1'! permits the return of the excess fuel.

By this means it is now apparent that clean air (or other non-explosive medium) positively supplants the foul gases; that the speed of action toward completely filling the cylinder with clean air, i. e. completely scavenging, depends only on the pressure of air when admitted to the cylinder; that further clean air is assured by the provisions for opening the valve 2| as the air will then enter the top of the'cylinder to assist purging, as above explained, stopping when the valve 2! closes; that when the valve ii is timely closed it entraps the clean air in the cylinder when the proper predetermined volume occurs therein; 5 and that the gas vapor is then added in proper and regulatable proportion to form an explosive mixture of the desired proportions, when the charge so formed is compressed and fired.

It is to be understood that many variations may be made in my improved engine without departing from the spirit of the invention as outlined in the appended claims.

Having, therefore, described my invention what I claim and desire to secure by Letters Patent, is:-

I. In an internal combustion engine, the combination with a cylinder, a piston, and an exhaust port adapted to be opened by the piston at the lower end of its stroke, of a scavenging port 20 disposed with relation to the exhaust port to be opened by the piston later than that of the exhaust port, an air supply, a valve controlled metering port adapted to be closed by the piston at the upper end of its stroke, and having com- 25 munication with said scavenging port, means to supply air under pressure from said supply joint 1y to said scavenging and said meter ports, means to timely actuate the valve of said meter port to admit air to the cylinder therethrough; meter 30 the amount of air therein; and return the excess air to the air supply, means cooperable with said actuating means during the compression stroke to supply in proper portion an amount of fuel to the amount of metered air to form the required explosion, and means, including a spray nozzle adapted to be covered by the piston at the upper end of its stroke.

2. In an internal combustion engine, the combination with a cylinder, a piston, and an exhaust port adapted to be opened by the piston at the lower end of its stroke, of a scavenging port adapted to be opened by the piston later than that of the exhaust port, and positioned opposite said exhaust port, a valve controlled metering port adapted to be closed by the piston at the upper end of its stroke, and positioned diametrically opposite to said exhaust port, and having communication with said scavenging port when said valve is open, means to supply air under pressure jointly to said scavenging and said meter ports, a valve actuating mechanism adapted to actuate the valve of said meter port to admit air to the cylinder of said engine; meter the amount of air therein; and return excess air 55 to the air supply, and a fuel feed mechanism coacting with said valve actuating mechanism during the compression stroke of said piston, to admit fuel to the retained air therein in required proportion, said fuel feed mechanism including 60 a spray nozzle positioned to be covered for protection by the piston at the firing moment.

MARIO GENTILI.

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