US2048223A - Engine - Google Patents

Description

July 21, P SCOTT 2,048,223

ENGINE Filed Aug. 19, 1951 2 Sheets-Sheet 2 Patented July 21, 1936 UNITED STATES PATENT 'OFFICE ENGINE Philip Lane Scott, San Mateo, Calif.

Application August 19, 1931, Serial No. 557,963

20 Claims. (Cl. 123-32) My invention relates to improvements in internal combustion engines, and may be applied to improvements in two stroke cycle engines in which fuel is injected into the combustion space, and has particular relation to improving the efciency of the exhausting and scavenging processes, and in addition thereto improving the mixing of the injected fuel with air charge.

One object of my invention is to provide simplified means for exhausting the products of combustion from a two-cycle engine cylinder especially during the early high pressure period of the exhaust. Anotherobjectistoprovidesimplemeans for admitting a smooth iiow of scavenging air to the cylinder. Another object is to provide means for decreasing the time required to expose adequate port area for scavenging or exhaust. Another object of the invention is to provide positive means to obtain turbulence and thereby mixing between the atomizing fuel and the air charge.

Other objects will appear from time to time during the course of the specifications and claims.

For the purpose of showing one application of my invention to an engine I have used a twocycle engine construction showingonly the cylinder, piston and the cylinder head as these are the parts particularly involved in the invention. The engine is otherwise assumed to have conventional parts such as the crank shaft and housing, cam or layshaft, air supply, exhaust manifold, fuel supply and the like which are not shown as they form no special part of the invention. Since the application of the principles involved may take a wide variety of forms and since the structures will have a variety of adaptation, these drawings are in a sense diagrammatic and it will be understood that other applications and adaptations may be used without departing `from the spirit of the invention. y

Figure 1 shows a vertical cross-section of a twocycle engine cylinder;

Figure 2 shows a section in plan along the line 2-2 of Figure l;

Figure 3 shows a vertical section in elevation of a modified form.

Like characters refer to like parts throughout the specications and drawings.

Referring to Figure l, A is an engine cylinder provided with a series of ports A1 which may be at approximately its mid position.

B is a piston adapted to reciprocate within the cylinder A. B1 isa depression within the head of 'the piston B defining in conjunction with other parts a combustion space. On its outward stroke the piston B will reach in its lower position, the

lower edges of the ports A1. A2 are the leading or timing edges of the ports A1.

C isv a cylinder head adapted to receive fuel atomizing valve C1 and having within it a charnber C2 which opens freely at its lower end into the bore of the cylinder A. C3 is a series of ports positioned at some desired distance away from the end of the chamber C2. C4 is a gas belt about the chamber C2 in communication with the ports C3 and adapted to convey gases to or from the ports C5. C5 are the leading or timing edges of the ports C3. C6 is a piston adapted to reciprocate within the chamber C2. CI is a roller mounted within the piston CB providing a member against which a cam D may act. The cylinder head C is .provided with a specially formed lower surface C2 between the head C and the piston B and con- I nects the chamber C2 and the combustion space B1. Upon the cam D are the two working faces D1 and D2 respectively, a segment D2, and a receding face D2. D4 is a shaft upon which the cam D is fixed and upon which the driving gear D5 is also fixed. This cam may be driven in any suitable manner in phase with the engine shaft (as for instance by a vertical drive shaft and an appropriate bevel gear train). This drive is not shown as it forms no part of the invention. Fuel V is supplied to the nozzle C1 by any conventional fuel pump whichis not shown as it forms no particular part of the invention.

Referring to the form shown in Figure 3, there is a cylinder A and a piston B similar to the form shown in the gures in Figure l.

AI is a series of ports located around a portionof the cylinder wall preferably at the lower pstonposition. A8 are the leading or timing edges of these ports. A3 is a second series of ports also located around a portion of the cylinder Wall opposite the ports A". The ports A'I and A3 are connected with the manifolds A5 and A5. C1 is a fuel atomizing valve located within the head C. C19 is a combustion space formed within the cylinder head C. C1o is a gas duct connecting the chamber C19 with the chamber E2. E3 are ports located in the wall of the chamber E2. The ports E2 lead into a manifold E4 adapted to communicate with external piping. These ports have leading edges E5. Adapted to reciprocate Within the chamber E2 is the piston yE5 driven by the connecting rod C11, the arm C12 positioned on the driven in phase with the engine crank shaft by any suitable train of gears. D is a cam, which, as shown, is identical in form with the cam shown in Figure 1, attached to said crank shaft having the Working faces D1 and D2 which act upon the roller D10 journaled in the fork C16 attached to the end of the push rod C15. lThe cam has receding faces D3 and D9.

The useand operation of my invention ist'as follows:

The process and apparatus of my invention may be used in connection with almost .any internal' combustion engine. Possibly -they lend themselves particularly well to use in connection with a two-cycle engine and for that reason the engine shown in the drawings is a two-cycle engine. The invention, however, is in no sense limited to use in connection with such an engine.

In the form shown in Figures 1 and 2, though only an engine cylinder and piston are shown it is assumed that the remaining parts comprise a complete two-cycle engine structure. Any suitable exhaust ducts, scavenging air supply, starting means and the like are presupposed. With the parts in the position shown in Figure 1, fresh air is being introduced into the cylinder andthe residue of spent gases of the previous combustion are being blown out. The scavenging air may be introduced through the ports A1, pass upwardly through the cylinder and out through the ports C3 but it may equally well be arranged that the scavenging air enters through the port C3 and discharges through the ports A1. Upon commencing of this process the power piston B moves upward until its edge coincides with the timing edges A2 of the ports A1 simultaneously the piston C6 is depressing in its cylinder C2 until its forward edge coincides with the edges C5 of the ports and closes them. During the next portion of the cycle the piston C6 remains stationary, its motion being determined by proper design of the cam D which first moves the piston relatively rapidly to close the ports and `lthen holds it stationary while the power piston B completes its compression stroke. As the power piston B approaches the top of the cylinder the depression B1 in the head of this piston will tend to form with the generally fiat surface C8 of the cylinder head a hemispherical combustion space. However, the cylinder C2 is so positioned in the head that a small portion yof its projected area registers with the -depression B1 forming a restricted passage between the cylinder C2 and the combustion chamber B1. This restricted passage formed only when thepower piston is in 'the upper portion of its stroke is for the purpose of restricting the expulsion of air from the cylinder C2 and producing a high velocity of air current in B1 at some desired time, at or near the end of compression. Fuel is injected through the fuel valve C1 into the combustion chamber B1. For general purposes this fuel may be fully atomized by the action of the fuel nozzle C1, though this feature is not in all -cases an essential part of the invention. Simultaneously withthe. delivery and. atomization of the fuel into the chamber B1 the piston C6 is again moved` -forward by a second face upon the .cam D. In most cases this action will be timed "substantially to coincide with the introduction of the fuel and 2,048,223 -shaft C12, and the off-set crank C14. l This crank will be prolonged to a time substantially correspending to the introduction of the fuel. By this action of the piston C6 the portion of the air charge which was held Within the chamber C2 is readily expelled through the restriction into the combustion space B1. It is the purpose of this rapid expulsion to set up a positive definitely directed strong current of air within the combustion space during the period of injection.

For the purpose of assuring a thorough and complete mixture .of all the atomized fuel, with all the air available for combustion, it is obvious that a wide variety of arrangements of these 'parts may be made to accomplish the ,same result without departing from the spirit of the invention, the principle being that there shall be a positive discharge of air into the combustion space substantially at the time of the introduction. of the -fuel and in such a way as to best promote mixing the air and fuel. vious that this discharge or supercompre'ssion may have several secondary eiects, such as some additive eifect in atomizing the fuel and perhaps raising the compression to a point at which ignition will occur provided thatit has not been accomplished -by the motion of the power piston. The mixing and burning of the charge having been accomplished as described, the expansion of the gases takes place driving the power piston downward on a power stroke. Duringl this. power stroke the piston C6 remains stationary in its downward position until the predetermined point vis reached at which exhaust is to take' place. ,At

this point the cam D has rotated to bring a high velocity receding face into action,permitting the piston C6 to drop backward rapidly under the influence of the gas pressure, exposing the ports C3 rapidly. Exhaust takes place .for the most part through these ports. Upon the release of the exhaust pressure ranged that the power piston B will then have reached the leading or timing edges A2 of the scavenging ports A1, as these ports arevopened the scavenging air enters around the entire periphery and sweeps the remaining burned gas ahead of .it through the exhaust ports c3 and the manifold C4.

This type Aof construction may equally :well be h used for a flow 4of exhaust and ineither direction, specifically be used for exhaust ports and be used for scavenging ports.-

the combustion chamber, the auxiliary piston C6 above of the mixing scavenging gases the ports A1 may the ports C3 may TheI formation of operation of the of fuel and air is,'however,

`the same for both directions of gas flow. In the case that the ports A1 servefor exhaust then the lIt is ohto a point slightly below' that of the scavenging air the parts are so ar.-

and the process described cam D with its drive is so arranged as to hold the purpose as previously described with respect to v the mixing of fuel and air but its further function of 4serving as a piston valve is restricted to providing only for the 'quick reduction of exhaust pressures'. It is not readily' adaptable to serve 'as a scavenging control inthe formshown in during the high pressure portion of exhaust.

Figure 3. In this construction the cylinder has at its lower end two sets of ports, a group A3 leading from the manifold A6 serving as scavenging ports and second group A7 of exhaust ports leading into the associated manifold A5. The cycle of operation for this system comprises first the charging of the cylinder with fresh air from the ports A3 throughout the combustion space and out the ports A7 andalso throughout the combustion chamber C19, which, in this form, is formed within the cylinder-head, the passage or duct C10, the chamber E2 and the ports E3 into the manifold E1. This charging being complete the power piston having risen to a point to cover the ports A3 and A7, the auxiliary piston E6 isv then brought forward by means of its driving linkage consisting of the connecting rod C11, the lever andthe off-set crank C12 and C14, the relier D10 and nauy the cam D which is driven through its shaft and the gear D11 from the engine by any suitable gear train. The piston E6 having moved forward to cover the ports E3, it then remains stationary since the cam D has an inactive face lying between the working face D1 and the succeeding working face D2. The power piston B substantially completes its compression stroke whereupon fuel is introduced at the proper time through the valve C1 into the combustion chamber C19. As in the previous structures the piston E6 is then advanced through its drive by means of the second working face D2 on the cam D. This results in a sudden evacuation of air from the cylinder E2 through the air passage C1 and into the combustion chamber C19. The general purpose of this evacuation is the same as that heretofore described. It is intended to effect a substantially complete mixture between atomized fuel and air during the time of injection and combustion. Upon the completion of combustion the expansion of the gases takes place driving the piston B on its outward or working stroke. At some time, somewhat prior to the opening of the ports A7, by the coincidence of the piston head with the timing edges A11 of the ports, the auxiliary piston E6 is permitted to recede suddenly by the cam D. In one form this quick recession is accomplished by the face D9 of the cam. The sudden movement of the piston E6 to its outermost position suddenly uncovers the high pressure exhaust ports E3, which, though relatively small in area are able to pass a portion of the exhaust gases quickly As in the first design, when the exhaust pressures in the cylinder have subsided suiciently, the mechanism is so arranged that the piston B will uncover both the ports A3 and A7 permitting the scavenging to take place and providing additional port area through which the relatively low to sweep the cylinder entirely clear of spent gas without appreciable intermingling between fresh air and spent gas and without loss of fresh air. There is the further important problem unrelated to the scavenging process of securing a thorough mixture of the fuel with all the air.

In the common construction of a two-cycle engine cylinder wherein scavenging and exhaust are accomplished through two sets of ports located at the base of the cylinder, it is obvious that the timing and rapidity of exposure of port area of exhaust will be a direct function of the piston motion. It is also obvious that the scavenging air must follow a relatively tortuous path within the cylinder which unavoidably results in following up the fresh a`ir with burned gas. In both forms of my invention as shown the initial high pressure stages of exhaust are taken care of by a piston valve or. its equivalent, which, being cam controlled may have a much more rapid opening than a port controlled by the working piston. This feature either directly or indirectly increases the length of the power stroke of the piston to an appreciable degree. In both forms of the invention the apparatus which accomplishes this desirable result of shortening the exhaust period also performs an entirely separate important function, namely, that of creating a piston controlled and timed turbulence coincident with the introduction of the atomized fuel to promote thorough mixing between the fuel and the air. As is seen from the previous descriptions, the result is accomplished by dividing the stroke of the piston valve into two parts by the shape of the driving cam and using the second portion of the stroke to supercompress a portion of the main air charge which lies within the cylinder containing this auxiliary piston. This supercompression expels this air at the desired time and in the desired direction with any desired velocity into the combustion chamber coincident with the introduction of fuel and in a..

ow which is known to be a. highly desirable feature. It is also seen that this flow may take place in either direction if the scavenging air is introduced through the ports in the auxiliary cylinder, the only change is a change in the timing and contour of the driving cam. A further advantage of such construction lies in the fact that with one mechanism controlling gas flow available for timing independently of the main piston such additional operations as super-charging the cylinder by means of delayed closing of the scavenging air is to some degree uniow and that this operation makes possible complete clearing of the cylinder and the combustion space of burned gas. Al- .though the engine shown is of a type suited for operation with compression ignition yet this proprovision for positive mixing of air and fuel may equally well be applied to engines using other forms of ignition.

I claim:

1. The process of operating an internal combustion engine having a main combustion chamber and an auxiliary combustion chamber, which includes the following steps: introducing'a main air charge into the main combustion chamber, compressing it within said combustion chamber, forcing a portion of it into said auxiliary chamber, atomizing and discharging fuel generally into the main air charge and supercompressing that portion of the air charge free of fuel within the auxiliary chamber, and evacuating the auxiliary chamber by positively forcing the supercompressed air from the auxiliary chamber into the path of the fuel substantially simultaneously with the atomization of fuel, burning the fuel, expanding the products of combustion within the chamber and cylinder, relieving pressure in the auxiliary I cylinder, a fuel valve positioned within said head and adapted to discharge atomized fuel into said cylinder, a chamber associated with and of smallercapacity than said cylinder, ports arranged within the wall of the chamber, a secondarypiston adapted to reciprocate in said clamber, to

open and close said ports and means for reciprocating said second'piston in timed relation to the power piston and the discharge of fuel to expel the contents of said chamber and to create regular air flow in said head'during the period of fuel injection.

3. In an internal combustion engine, a cylinder and piston and separated openings comprising two separate points of exhaust, one of said points of exhaust being located within the cylinder and the other point of exhaust being located beyond the coni'lnes of the cylinder and piston means for i `controlling the said opening beyond the connes of the cylinder and associated with said cylinder for additionally compressing the main charge of air within said cylinder.

.4. In an internal combustion engine, a main power cylinder and piston, an auxiliary cylinder and piston, an open passage connecting the two, means in the auxiliary cylinder for discharging burnt gas, and additional means in the main cylinder for discharging burnt gas.

5. In an internal combustion engine, a power cylinder and piston, an auxiliary cylinder and piston, said auxiliary cylinder being ported, said auxiliary piston mounted to move to uncover said port to exhaust burned gas, the power cylinder being ported to provide intake and exhaust passages and the power piston arranged to move to uncover said ports to admit a charge of fresh air and exhaust burned gases and to compress the fresh air charge within the power cylinder.

6. The process of'burning fuel in an internal combustion engine having a main power cylinder and piston and a secondary cylinder and piston,

the two cylinders being freely open to each other which process includes the following steps: inducing air into the mai cylinder above the piston, injecting fully atomized fuel into this air, burning the fuel and air, controlling ejection of a portion of the burned gases by the movement of said secondary piston and controlling the ejection of the remainder of the burned gases by thel movement of said main piston.

7. The process of exhausting gases from an internal combustion engine having twoy exhaust ports and two moving piston means controlling said ports, which process includes the controlling of the exhaust in two separate and distinct stages, the first by one of said means and along one pathand the second by the other of said means and along theother path.

.8. The process of controlling the flow of gases in the cycle of operation of an internal combustion engine having a main cylinder and an auxiliary chamber which includes: introducing an air |charge into the main cylinder, compressing' said charge therein, forcing. a portion of said charge into the auxiliary chamber, introducing a fuel charge, supercompressing the air within the auxiliary chamber and positively forcing the supercompressed air into the main cylinder, burning.

the fuel, expanding the resulting products of combustion within the maincylinder and auxiliary chamber, initiating the release of the high pressure burned gases from the auxiliary chamber during an early period of the cycle of operation, and subsequently, at a later period of the cycle, further releasing the high pressure burned-gases, and introducing fresh air into the cyinder and auxiliary chamber.

9. The process of controlling the ow of gases in the cycle of operation of .an internal combustion engine having a main cylinder and an auxiliary chamber which includes: introducing an air charge into the main cylinder, compressing said charge therein, forcing a portion of said charge into the auxiliary chamber, introducing a fuel charge, supercompressing the air within the auxiliary chamber and positively forcing the supercompressed air into the main cylinder, burning the fuel, expanding the resulting products of combustion within the lmain cylinder and auxiliary chamber, initiating the release of the high pressure burned gases from the auxiliary chamber during an early period of the cycle of operation, and subsequently, at a later period of the cycle, further releasing the high pressure burned gases,

and simultaneously introducing fresh 'air into the,

cylinder. A

10. The process of controlling the flow of gases in the cycle of operation of an internal combustion engine having a main cylinder and an auxiliary chamber which includes; introducing an' air charge into the main cylinder, compressing said charge therein, forcing a portion of'said charge into the auxiliary chamber, introducing a fuel charge, supercompressing the air within the auxiliary chamber and positively forcing the supercompressed air into the main cylinder, burning the fuel, expanding the resulting products of combustion within the main cylinder and auxiliary chamber, suddenly initiating the release of the high pressure burned gases from the auxiliary chamber during an early period of the cycle of operation, and subsequently at a later period of the cycle, further releasing the high pressure burned gases, and introducing fresh air into the cylinder and auxiliary chamber.

1l. The process of controlling the ilow of gases in the cycle of operation of an internal combustion engine having a main cylinder and an auxiliary chamber which includes: introducing an air charge into the main cylinder, compressing said charge therein, forcing a portion 'of said charge into the auxiliary chamber, introducing a fuel charge, supercompressing the air within the auxiliary chamber and lpositively forcing the supercompressed air into the main cylinder into the path of the entering fuel, burning the fuel, expanding the resulting products of combustion within the main cylinder and auxiliary chamber, initiating the release of the high pressure burned gases from the auxiliary chamber during an early ,period of the cycle of in the cycle of operation of an internalcombustheicylinder head and adapted to discharge attion engine having a main cylinder and an auxiliary chamber which includes: `introducing an air charge into the main cylinder, compressing said charge'therein, forcing a portion of said charge into the auxiliary chamber, introducing a fuel charge, supercompressing the air Within the auxiliary chamber and substantially simultaneously with the fuel introduction 'positively forcing the supercompressed air into the main cylinder into the path of the entering fuel, burning the fuel, expanding the resulting products of combustion within the main cylinder and auxiliary chamber, suddenly initiating the release of the high pressure burned gases from the auxiliary chamber during an early period of the cycle of operation, and subsequently at a later period of the cycle, further releasing the high pressure burned gases, and simultaneously introducing fresh air into the cylinder.

13. In an internal combustion engine including a main cylinder having a cylinder head and a main piston mounted for reciprocation within the cylinder, an auxiliary cylinder having free communication with the main cylinder and an auxiliary piston mounted for reciprocation therein, said main piston and cylinder head cooperating when in upper dead lcenter position to define a combustion chamber having restricted communication only with said auxiliary chamber, and means for evacuating the auxiliary chamber substantially simultaneously with the formation of said combustion chamber and restricted passage.

14. In an internal combustion engine. including a main cylinder and a piston mounted to reciprocate therein, an auxiliary cylinder and an auxiliary piston mounted to reciprocate therein, cooperating means associated with the main piston and cylinder head for alternately forming a combustion chamber having a restricted entrance passage thereto, and a Afree gas passage -between the main cylinder and the auxiliary cylinder, and means to relatively move said pistons within the respective cylinders.

15. In combination in a two-cycle internal combustion engine, a main ported cylinder provided with a plurality of ports adapted to control gas flow, a power piston mounted within the cylinder and adapted to reciprocate past said ports to control them, said cylinder including a cylinder head, an auxiliary chamber provided with a plurality of portsadapted to control exhaust gas'iiow, an auxiliary piston slidably mounted in said chamber and 'adapted to slide past said ports to control gas iiow therethrough, a spray valve niunted inthe cylinder head adapted to discharge atomized liquid fuel, and means for driving the auxiliary piston to increase the pressure in the cylinder during a portion of the combustion period of the engine.

16. In combination in a two-cycle internal combustion engine. a main ported cylinder provided with a plurality of ports adapted to control gas ow, a power-piston mounted. within the chamber and adapted to reciprocate past said lports to control them, said cylinderhaving 'a 'cylinder head, an auxiliary chamber having communication with the main cylinder and provided with a plurality of ports adapted. to control exhaust gas iiowa spray valve mounted in omized liquid fuel, an auxiliary piston mounted in the auxiliary chamber adapted to slide past said ports to control them, and means for moving the auxiliary piston in timed relation to the mainpiston to evacuatethe auxiliary chamber 5 into the main chamber during theV period of fuel injection.

17. In combination in a two-cycle internal combustion engine, a main ported cylinder provided with a plurality of ports adapted to control exhaust gas iiow, a power piston mounted within the cylinder and adapted to reciprocate past said ports to control them, a cylinder head adapted to form with said piston a combustion chamber, an auxiliary chamber formed in said 15 cylinder head provided with a plurality of ports adapted to control gas flow, said auxiliary chamber having free communication with the main cylinder, an auxiliary piston "mounted in said auxiliary chamber adapted to slide past said 20 ports to control them, a spray valve mounted in the cylinder head and adapted to discharge vatom'ized liquid fuel into said combustion chamber, and means for intermittently driving the auxiliary piston with respect to the continuous 25 motion of the main piston to evacuate the auxiliary chamber and forcibly discharge the contents thereof intov said combustion chamber concurrently with injection of fuel thereinto.

18. In aninternal combustion engine, a cylinder, a cylinder head, a working piston within said cylinder', an auxiliary chamber ,associated with the cylinder and having an auxiliary piston mounted therein, said cylinder head and working piston when in position of substantially maximum compression cooperating to form a combustion chamber having a restricted gas passageway leading into theauxiliary chamber, and means for actuating the auxiliary piston and moving gas contained within the auxiliary chamber through said` passageway into the combustion chamber,` said formation of the 'combusi tion chamber and restricted passageway occurring only'during a portion of the engine cycle.

19. In an internal combustion engine, a cylindet and a cylinder head, a Working piston mounted within said cylinder, an auxiliary chamber having free communication with the cylinder, an auxiliary piston mounted within the auxiliary chamber, the cylinder head and said working piston, when the latter is in substantially upper dead center position, cooperating to -form a combustion chamber having a restricted .iliary cylinders, said means'including cooperative elements formed on the piston' and cylinder head, and means for displacing the contents of lsaid auxiliarycylinder into the mainv cylinder. Pima? LANE sco'r'r.

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