US2085035A

US2085035A - Internal combustion engine

Info

Publication number: US2085035A
Application number: US749367A
Authority: US
Inventors: George W Meredith
Original assignee: Individual
Current assignee: Individual
Priority date: 1934-10-22
Filing date: 1934-10-22
Publication date: 1937-06-29
Anticipated expiration: 1954-06-29

Description

June 29, 1937, aw, M H 2,085,035

INTERNAL COMBUS TION ENGINE Filed Oct. 22, 1954 3 Sheets-Sheet l June 29, 1937.

G. W. MEREDITH INTERNAL COMBUSTION ENGINE Filed Oct. 22, 1934 3 Sheets-Sheet 2 June 29, 1937.

G. W. MEREDITH INTERNAL COMBUSTION ENGINE 5 Sheets-Sheet 3 Filed Oct. 22, 1934 Patented June 29, 1937 ire r'rEs wears PATE'E FE'EQE 8 Claims.

The two-cycle type of gas engine (the term gas engine being hereinafter employed as synonymous with internal-combustion engine), While extremely simple from the standpoint of the mechanism therein employed, is ordinarily deficient in performance and in fuel economy when operated under loads which are small fractions of the engines full load capacity. Furth rmore, the two-cycle does not run smoothly at low throtn tle except it be supplied with a mixture overrich in fuel in order to ensure ignition of the mixture. The latter defect in operation is due to the difiiculty of providing an ignitable mixture at the igniter, because of the preponderance L", of burned gas remaining in the cylinder, the

result of a previous explosion. It is characteristic of the two-cycle gas engine that the compression pressure is approximately the same at low throttle as at full throttle, for the reason that the partial vacuum, produced in the cylinder by throttling the mixture, will draw gas into the cylinder from the exhaust passages.

The engine hereinafter described and illustrated in the accompanying drawings was invented for the purpose of securing an engine which would not be subject to the objections above enumerated. It is similar in several respects to the engine illustrated and described in my prior application filed Aug. 31, 193A, and bearing Serial No. 742,277, series of 1925. In the present engine, I have incorporated the features of the engine which is the subject of my prior application, and have added thereto certain additional features hereinafter illustrated and described.

As in the engine described in my prior application, one object of my invention is to provide means whereby a more intimate mixture of the fuel and the air may be secured than is customarily obtained in two-cycle engines in general use. Another object is to secure a certain measure of stratification between the new charge and such exhaust gases as may remain from a previous explosion. Another object is to secure, by this stratification, a certain measure of isolation of the fresh charge from residual exhaust gases in proximity to and surrounding the first point of. ignition. Another object is to provide unidirectional flow of the exhaust gases and the entering charge thereby to minimize dilution of the latter by exhaust gases. In addition to the above objects, the invention which is the subject of the presen application has for its object the securing of a greater freedom for the entering charge, and a fuller distribution of the charge throughout the cylinder.

In processing my invention, I retain the passage between the crankcase and the closed end of the cylinder as in my prior application, and in addition thereto I incorporate in the cylinder wall a by-pass similar to that employed in the majority of two-cycle engines, together with the by-pass port customarily provided in such engines. I retain the piston port provided in my prior design, and arrange it so that it will register with the entrance to the pass-age at the end of the power stroke. I also provide an exhaust port in the cylinder wall on that side of the cylinder opposite the passage. I attach to the piston a deflecting plate, of the same general type customarily employed in two-cycle engines. As the piston approaches the end of the power stroke, it first opensthe exhaust port, then the passage port, and finally the by-pass port. As mixture enters the cylinder from the by-pass, it is deflected toward the closed end of the cylinder by the deflecting plate attached to the piston. As this portion of the new charge meets that entering the closed end of the cylinder'frorn the passage, eddies are promoted to increase the turbulence, which is promoted at the entrance of the fresh charge into the cylinder from the passage as follows:

The exit from the passage into the closed end of the cylinder is so directed that the path of the entering charge is pointed toward the wall of the cylinder in one type of admission port and toward the wall of the cylindrical mouth of a second type of admission port. Thus the column of entering gas is induced to follow a path tangential to the cylindrical surface and thereby go into a spiral swirling motion. As this portion of the charge meets that entering from the by-pass, turbulence in all directions is promoted. The intimacy of the mixture promoted by the turbulence tends toward perfection of combustion, high means effective pressures and maximum economy of fuel.

The passage referred to is provided in the wall of the cylinder, and provides a conduit for the mixture to flow from the crankcase to the closed end of the cylinder. The cylinder end of the passage is open at all times to the cylinder and in it is comprised a portion of the combustion space, into which the mixture is compressed at the end of the compression stroke. Since the combustion space is comprised of both the passage and the clearance between the piston and the cylinder head at the end of the compression stroke it is of an attenuated form. This requires special arrangement of the ignition means.

As in the engine described in my prior applito provide the necessary seal.

cation, I so locate the spark plugs or other ignition means that one is located close to the passage port and another in proximity to the exit from the passage into the cylinder. Since the rush of the fresh mixture entering from the crankcase will drive from the passage any products of combustion remaining from a previous explosion, there will be fresh mixture, undiluted by exhaust gases, in proximity tothe passage port. Therefore, the points of the spark plug located close to the passage port will be surrounded by fresh mixture, and ignition be assured regardless of how low the engine may be throttled. Thus the skipping of explosions, or missing which is a characteristic of both twoand four-cycle engines at low throttle, is avoided.

Owing to the attenuated form of the combustion space, ignition by one spark plug alone, especially if the plug is located near one end of the combustion space, would cause a long period of inflammation. If but the one plug at the entrance to the passage were to be used, flame propagation to opposite end of the combustion space would be slow, and the performance of the engine would be sluggish. The second plug at the exit of the passage into the cylinder provides for rapid spread of combustion and a short period of inflammation.

The filling of the passage with fresh mixture is assured for the reason that the passage port is opened in advance of the by-pass port, and therefore at a time when the pressure in the crankcase is at a maximum.

When the piston port is out of registration with the passage port, the passage port is closed by the outer surface of the piston wall. Since the piston must be free to reciprocate in the cylinder, there must be a certain amount of space between the piston and the inner wall of the cylinder. This space increases as the piston and the cylinder wear from use. Were no means provided to seal this space, gas under pressure of the explosion would enter, and pass around the piston to the exhaust port. Piston rings offer a means However, in order to provide suficient sealing, it would be necessary to provide rings around almost the entire length of the piston. Fortunately, means presents itself for providing the required seal without resort to a multiplicity of piston rings.

During the compression stroke, pressure is not generated in the cylinder until the piston has covered the exhaust port. Half the remaining stroke is completed before the pressure is of appreciable amount or about 20 pounds gauge. The lubricating oil should provide ample seal against the escape of gases under this low pressure. For the remainder of the compression stroke, piston rings may be provided for sealing the annular space. However, during the power stroke, the pressure at the moment the piston uncovers the exhaust is between 40 and pounds per square inch. While rings provided to care for the end of the compression stroke will suffice for the early 7 portion of the power stroke, the pressure in the cylinder and in the passage is considerable up to the moment the exhaust port opens. In the operation of any engine, the angularity of the connecting rod during the 7 major portion of the stroke causes the pressure against the end of the piston to be transierred in part to, the cylinder wall through the piston, and against that wall of the cylinder which is on the side opposite the position of the crankpin during the stroke. If the ratio of the pressure of the piston against the cylinder wall to that against the end of the piston is greater than the ratio of the area of the passage to the area of the piston, adequate sealing will be provided. Analysis of these ratios will show that after the piston has traversed 15 per centum of the power stroke, the pressure of the piston against the cylinder wall is in excess of 15 per centum of that against the end of the piston. Hence, if rings are so located on the piston that they are between the exhaust port and the passage port until the piston has made 15% of its power stroke, the area or" the passage port may be fully 15% that of the area of the piston. Therefore, by so directing the rotation of the crankshaft that the crankpin is that side of the axis of the cylinder extended opposite the passage port during the power stroke, a multiplicity of piston rings will not be required.

In the accompanying drawings, I illustrate three types of exit of the passage where it joins the closed end of the cylinder. In one the flow is from the passage along a plane at a right angle to the axis of the cylinder. In another, the mouth of the passage is directed along the axis of the cylinder. types of passage mouth are arranged in combination.

In the drawings:

Fig. l is an elevation in section of one form of my improved engine, the section being taken along line il of Fig. 3. In the figure, the mouth of the passage is along a plane approximately normal to the axis of the cylinder. The piston is shown at the end of the compression stroke.

Fig. 2 is an elevation in section of the engine of Fig. 1, the section being taken along line 22 of Fig. 4. In this figure, the piston is at the end of its power stroke.

Fig. 3 is a plan in section of the engine of Figs. 1 and 2, the section being taken through the combustion space along line 3-3 of Fig. 1.

Fig. i is a plan in section of the engine shown in the previous figures, the section being taken along line 1-4 of Fig. 2, and as this section would appear with the piston in the position of Fig. 2.

Fig. 5 is an elevation in section of an alternate form of my invention, the section being taken along line 5-Ei of Fig. 6. In this figure the piston has started to open the passage port as it nears the end of the power stroke.

Fig. 6 is a plan in section of the engine of Fig.

5, the section being taken along line 6-6 of Fig. 5.

Fig. '7 is a fragmentary sectional elevation of another alternate form of my improved engine,

the section being taken along line 'i-l of Fig. 8.

Fig. 8 is a plan in section of the engine of Fig. 8, the section being taken aong line 38 of Fig. 7.

Figs. 9, l0 and 11 are diagrammatic representations of the sequence of the positions of the piston as the various ports are opened toward the end of the power stroke.

Similar numerals refer to throughout the several drawings.

In the figures, the cylinder is designated by the numeral B2. In diagrams tii it is shown at tached to crankcase 33. Within the cylinder is the piston l5, provided with th port i5 adapted to establish communication between the interior of the piston and the passage provided in the wall of the cylinder, when port 55 is in registration with the passage port ii. Through the interior of the piston, communication is established between the crankcase i3 and passage l6,

similar parts In a third arrangement, the above two as illustrated in the diagram Fig. 10. Passage 7;

lB extends lengthways of the cylinder; and joins the closed end of the cylinder by way of the mouth is or H3 or both in combination asshown in Fig. 7.

In the wall of cylinder I2, is provided the bypass Zil partitioned from passage it The by-pass is in direct communicationwith the crankcase I3, and is provided'with the by-pass port 21 in the wall of cylinder E 2. Integral with piston M is the deflecting plate. 22, adapted. to direct the gases entering the cylinder from port 29 toward the cylinder head. Diametrically opposite port there is provided the exhaust port 23 in the wall of cylinder I2. Spark plug 2d provides for ignition of that portion of the mixture in. the immediate vicinity of port I11, and spark plug 2 3' provides for ignition of themixture in clearance space [9 (Fig. 1);

Piston It is linked to the crankshaft 25 by means of the connecting-rod 26, the lower end of rod 26 being journalled to crankpin 21 and the upper end of the rod journalled to piston pin 28. The piston is provided with three sets of piston rings. Rings 29 function to seal the outer end of the piston M, as is customary in all gas engines. Rings 39 seal thatend of the piston nearest the crankcase l3. Rings 3| function. to seal the passage'between the piston and the cylinder against flow of gases from port H. to port 23, during the later portion of the compression. stroke and the early portion of the power stroke. The position of rings 3| in relation .to ports I7 and 23 should be noted in Fig. 1. Attention is directed to the direction of rotation of the crankshaft, as indicated by the curved arrows, in relation to the position of the passage port ll, (Figs. 5, 9, l0 and 11).

In the cylinder and the various passages and ports in communication therewith, the fresh mixture of fuel and air is designated by arrows with shanks of solid lines, while exhaust gases are designated byarrows having shanks comprisedof broken lines.

In the operation of my improved engine, a combustible mixture of fuel and air is charged a into the crankcase or other pre-compression chamber by one of the several methods customarily provided therefor. The exact method of charging the crankcase or pre-co-mpression chamber is immaterial to the operation of an en.- gine incorporating my improved construction. The following sequence of operations comprises the remainder of the cycle.

A charge of fuel and air having been ignited in the combustion space, the ensuing explosion drives the piston toward the crankcase, and compresses a mixture of fuel and air trapped. in the crankcase. As the piston approaches the end of this, the power stroke, it uncovers exhaust port 22 as shown in Fig. 9, and the pressure within v the cylinder drives the products of combustion outward through the port. Further movement of the piston carries it to the position of Fig. 10 with port E5 in registration with port H. The pressure within the crankcase l3 drivesthe mixture therein through ports [5 and IT into passage !5 and, therethrough, into cylinder i2 through the. mouth 3. Further movementv of the piston uncovers port 2!, permitting gases from crankcase i 3 to flow into cylinder l2 through by-pass 26 and port 2|. As the enter.-' ing gases impinge against deflector 22, they are turned toward the closed end of the cylinder. During the next stroke of the piston, toward'the closed end of the cylinder, the ports 2],. I! and 23 are closed in the order given, and the mixture is compressed into the clearance space H! and the passage 16. Slightly in advance of the completion of the compression stroke, sparks are generated at the points of. plugs 24 and 24- igniting the mixture and starting another cycle.

As is well known in the art, the out-flow of exhaust gases through port 23 has a tendency, due to inertia, to produce a partial vacuum in cylinder 12. This effect, together with the new mixture entering through ports ll and 2! from the crankcase l3 insures a full charge of combustible mixture when the engine is operating at full throttle. When the entrance of fresh mixture to the crankcase is partially closed by throttling, the reduction of the volume of mixture within the crankcase results in a lowered pressure therein as compared to the crankcase pressure at full throttle, i. e-., when the entrance to the crankcase is fully open. Because of the low L crankcase pressure due to throttling the flow of freshv mixture through ports I! and 2| is reduced and may be so small as to be insufficient to fully overcome any vacuum in the cylinder.

Should the volume of fresh mixture entering passage l6" and cylinder I2 from crankcase 53 be insuificient to' raise the pressure in the cylinder to that of the atmosphere, the direction of flow of gases through port 23 will be reversed and exhaust gas-will enter the cylinder from the exhaust passages. This will result in the content of the cylinder becoming a mixture comprised of a considerable proportion of products of combustion, with little fuel and air. Asthe proportion of exhaust gases is increased; the ignition of the content of fuel becomes more difficult. It is customary, in the operation of the two-cycle engine, to insure ignition at lowthrottle by increasing the proportion of fuel in the mixture. This. results in-muchunburned fuel passing out through the exhaust port with. consequent high fuel consumption and a foul smelling exhaust. Another result of dilution of the fresh charge with exhaust gases is slow burning of the ignited fuel and the extension of the period of inflammation until the incoming charge is ignited and the mixture is fired prematurely with resulting explosions in the crankcase. This phenomenon, popularly known as back-firing, is one of the objectionable features of the two-cycle engine with base or crankcase compression.

It is evident to the most causal of observers that the engine herein illustrated and described will not be subjected to the diificulties of ignition above noted. No matter how low the engine may be throttled, there is certain to be fresh mixture, undiluted by exhaust gas, in that portion of' passage it near port 51. Hence, there will be assured an ignitable mixture surrounding the ignition points of spark plug 24 under all throttle positions. Thus there is assured smooth operation at low throttle because of the certainty of firing every charge even when the engine is idling without other load than the friction of its own mechanism.

In order to provide means for preventing the passage of gases from port ll around the piston to exhaust port 23, I provide piston rings 3!. With the crankshaft turning counterclockwise, as indicated by the curved arrow near crankshaft 25, the angul'arity of the connecting rod 26 will cause. piston 14- to be pressed against the wall of cylinder 12 on that side provided with exhaust port 23.. As hereinbefore described, pressure in the: cylinder does not begin to rise, during the compression stroke, until after port 23 has been covered by piston It. For a short space of the compression stroke the pressure generated around the piston from port ll to port 2 3.

is sufficiently low that the lubricating oil between the piston and the cylinder provides an ample seal to prevent the passage of, gases By the time the pressure in the cylinder and passage it has risen sufiiciently to cause leakage by the piston, rings 3i have passed port l1, and provide an efficient seal during the balance of the compression stroke.

During the power stroke, rings 3| seal against leakage between ports I1 and 23 until these rings pass port ll. By that time the piston has advanced sufficiently to swing the connecting rod 26 to an angle sufficient to cause piston l4 to be pressed against that portion of the cylinder wall contiguous to port I1, and with suflicient force to seal the contacting surfaces against leakage frcm port ll around the piston. This feature assumes increasing importance as the clearance between the piston and the cylinder increases with wear.

In the alternate form of my improved engine shown in Figs. 5 and 6, I have extended passage 56 across the top of the cylinder and provided it with a mouth l8 surrounding the axis of the cylinder extended. By this arrangement I promote stratification of the fresh mixture and the out-going exhaust gases. I also promote, by the arrangement of the mouth l8, the unidirectional flow of both the exhaust and the mixture entering the cylinder.

In Figs. 7 and 8 I show an arrangement of the exit from the passage l 6, with both the mouth [8 of Figs. 1-4, and the mouth l8 of Figs. 5 and 6 employed in combination.

I claim:

1. In a two-cycle gas engine, the combination with a cylinder provided with a conduit leading from a port provided in the cylinder wall midway in the length of the cylinder to the: space between the piston and the closed end of the cylinder when the piston is at the end of its compression stroke the conduit open continuously to the cylinder, of a piston reciprocating in the cylinder and provided with a port in its lateral wall adapted to register with the conduit port when the piston is at the end of its power stroke, a crankcase attached to the cylinder, the registration of the piston port with the conduit port adapted to provide communication between the conduit and the crankcase, a by-pass provided in the lateral wall of the cylinder and leading from the crankcase to' a second port provided in the cylinder wall midway of the length of the cylinder, an exhaust port provided in that wall of the cylinder diametrically opposite the by-pass port, and the piston adapted to uncover the ports in the following sequence; first, the exhaust port; second, the conduit port and third, the by-pass port. 3

2. In a two-cycle gas engine, the combination with a cylinder having a head attached to one end thereof and a crankcase attached to the other end and having a conduit provided in the lateral wall of the cylinder leading from a port provided through the wall of the cylinder midway of its length tothe interior of the cylinder just within the cylinder head the conduit open continuously to the cylinder, of a by-pass provided in the lateral Wall of the cylinder leading from the crankcase to asecond portprovided through the cylinder wall midway of the length thereof.

3. In a two-cycle gas engine including a cylinder fitted with a cylinder head closing one end of the cylinder and having a crankcase attached to that end of the cylinder opposite the cylinder head, a conduit provided in the cylinder wall and leading from a port provided through the cylinder wall midway of the length of the cylinder to an opening provided in the cylinder head into the cylinder, the said opening surrounding the axis of the cylinder extended the conduit open continuously to the cylinder, and a by-pass provided in the lateral wall of the cylinder leading from the crankcase to a second port provided through the wall of the cylinder.

4. In a two-cycle gas engine including a cylinder fitted with a cylinder head closing one end of the cylinder, a conduit provided in the wall of the cylinder leading from a port provided through the wall of the cylinder midway of the length thereof to a bifurcated opening provided in the cylinder and. the cylinder head the conduit open at all times to the cylinder, through both branches of said opening, one branch of said opening extending through the lateral wall of the cylinder immediately within the closed end of the cylinder, and the second branch of said opening extending through the cylinder head to an exit therefrom surrounding the axis of the cylinder K and into the cylinder.

5. In a two-cycle gas engine including a cylinder fitted with cylinder head closing one end of the cylinder and a crankcaseattached to that end of the cylinder opposite the cylinder head, a conduit provided in the lateral wall of the cylinder, the conduit extending through the wall of the cylinder head, the conduit leading from a port provided through the wall of the cylinder to a bifurcated exit therefrom into the cylinder, said conduit open continuously to the cylinder through both branches of said exit, one branch of the exit extending through. the lateral wall of the cylinder immediately within the closed end of the cylinder, the second branch of said exit opening from that portion of the conduit in the cylinder head into the cylinder, said branch of the exit surrounding the axis of the cylinder extended, and a by-pass provided in the lateral wall of the cylinder leading from the crankcase to a second port provided in the lateral wall'of the cylinder.

6. In a two-cycle gas engine including a cylinder with a cylinder head attached to one end of the cylinder, a conduit provided in the lateral wall of the cylinder leading from a port provided through the cylinder wall midway of the length thereof to a bifurcated passage provided in the cylinder and the cylinder head, one branch of said passage extending through the lateral wall of the cylinder immediately within the closed end of the cylinder, the second branch of said passage extending through the wall of the cylinder head to an exit therefrom provided in the cylinder head and surrounding the axis of the cylinder extended the conduit open at all times to the cylinder through both passages, an igniter located in the conduit near the port in the cylinder wall, and a second igniter located in that branch of the bifurcated passage in the cylinder head and near the opening therefrom into the cylinder.

'7. In a two-cycle gas engine, the combination with a cylinder provided with a conduit in the lateral wall of the cylinder, the conduit leading from a port provided through the cylinder wall midway in the length of the cylinder to the space between the piston and the closed end of the cylinder when the piston is at the end of its compression stroke the conduit open at all times and continuously to the cylinder, of a piston reciprocating in the cylinder and provided with a port through the lateral wall thereof, the piston port adapted to register with the conduit port when the piston is at the end of its power stroke, a crankcase attached to the cylinder, the registration of the piston port with the conduit port adapted to provide communication between the conduit and the crankcase, a by-pass provided in the lateral wall of the cylinder and leading from the crankcase to a second port provided through the cylinder wall midway of the length of the cylinder, and the by-pass partitioned from the conduit.

8. In a two-cycle gas engine, the combination with a cylinder provided with a conduit in the lateral wall of the cylinder, the conduit leading from a port provided through the cylinder wall midway in the length of the cylinder to the space between the cylinder head and the piston when the piston is at the end of its power stroke the conduit open at all times and continuously to the cylinder, of a piston in the cylinder adapted to reciprocate therein, a cylinder head attached to the cylinder and closing one end thereof, the piston provided with a port through the lateral wall thereof, the piston port adapted to register with the conduit port when the piston is at the end of its power stroke, a crankcase attached to that end of the cylinder opposite the cylinder head, the registration of the piston port with the conduit port adapted to provide communication between the conduit and the crankcase, a by-pass provided in the lateral wall of the cylinder, the by-pass leading from the crankcase to a second port provided through the wall of the cylinder midway of the cylinder wall, the piston adapted to uncover this second port when the piston is at the end of its compression stroke, and a deflector attached to the piston and projecting therefrom opposite the second port, when the piston is at the end of its power stroke.

GEORGE W. MEREDITH.