Internal Combustion Engine

Abstract

The detailed description and specification of this invention discloses a new four-stroke cycle internal combustion engine which is a new combination of previously used practices and a new method of inducting a charge into a cylinder in the course of an intake stroke. This method inducts a much greater charge, at a given high speed of the engine, than that inducted into any of today's engines of the same displacement, without the use of a supercharger, and eliminates the intake valves and the valve linkage used in conventional engines.

Description

This invention is an improved four-stroke cycle internal combustion engine.

Today, the customary engine of this class is a trunk engine with cylinders mostly in either "straight" or "V" arrangement and with two valves per cylinder of a size limited by their location which also keeps intake and exhaust valves in close proximity.

The oscillating connecting rod, of a trunk engine, intensifies tortional and engine unbalance vibrations and causes side thrusts which promote cylinder wall wear. To distribute this side thrust, a piston must have a skirt which makes the length greater than is required for a gas-tight seal only. This extra length requires corresponding extra length of the cylinder in which the piston slides.

The inherent equality of all strokes of a trunk engine limits the intake stroke to one-fourth of the four-stroke cycle. This causes a decrease in volumetric efficiency to start early as the duration of the intake stroke lessens at higher engine speed. The strokes are of equal length, as well as of equal duration, and it consequently is impossible to avoid a residue of hot gases at the end of the exhaust stroke which heats and dilutes the incoming charge during the ensuing stroke.

The "straight" or "V" cylinder arrangement, or any other arrangement possible in a trunk engine, is not compact.

The limitation of valve size limits breathing both intake and exhaust. The proximity of exhaust and intake valves causes an unfavorable transfer of heat from the former to the latter and causes inefficient breathing during intervals when exhaust and intake valves are open at the same time in the same cylinder. This valve proximity also causes manifolding complications. The valve locations are remote from the drive shaft, which is the source of power for valve operation, and require an extensive valve linkage which at minimum must include reduction gears and a camshaft with a cam for each valve and which has often such added parts as push rods, rocker arms on a shaft or shafts, and various bearings.

The main object of this invention is to provide an improved and new four-stroke cycle internal combustion engine which: will have no connecting rods and will have no crankshaft; will have an unbroken drive shaft driven by a single circumferential cam, operating in combination with roller followers connected to pistons by piston rods; will have guide and support members to guide the roller ends of piston rods; will have short pistons sliding in cylinders with axes parallel to the drive shaft; will have a cam face so shaped as to provide a long duration intake lasting more than one quarter of a cycle; will leave no residue in the combustion chamber at the completion of an exhaust stroke; will have a compact arrangement of its cylinders; will have only one valve at the top of a cylinder; will have on the engine drive shaft a single circumferential valve cam; will have an intake port near the bottom of a cylinder that together with the piston takes the place of an intake valve and its linkage; and will have simplified manifolding.

It is evident that the improved and new engine of this invention, of which the more important elements have just been outlined, has many advantages over today's usual engine some features of which were outlined and commented upon early in this summary. The more evident advantages include:

Less tortional vibration. A stiff unbroken drive shaft compared with a shaft broken by cranks and crank pins.

Little engine unbalance vibration. No oscillating connecting rod.

No side thrust of pistons against cylinder walls.

Shorter pistons and shorter cylinders. Skirts not required because of no side thrust.

Duration of intake stroke much longer. Better breathing at higher speeds increases power 20 percent.

No exhaust residue. Hence, improved combustion of the ensuing charge.

Axial arrangement of cylinders makes a compact engine.

Larger exhaust valve speeds exhaust.

No intake valve. Large intake port passes charge more freely than the usual intake valve.

Does not have exhaust and intake overlap.

Intake port and manifold are always cooler than the usual intake valve and manifold in close proximity to the hot exhaust.

Intake charge starts under pressure equivalent to 100 percent supercharge.

No valve linkage such as reduction gears, camshaft with individual cams, two for each cylinder, and often other elements.

Cooling interval after complete exhaust and before charge enters the combustion chamber.

Higher volumetric efficiency. Long duration intake.

Higher mechanical efficiency. Roller bearings and no piston side thrust.

Simpler lubrication. No valve linkage and no wrist pin bearings.

Better cooling. Duration of cool strokes (intake and compression) about 40 percent longer than hot strokes (power and exhaust) compared with equal in the usual engine.

Simpler structure with fewer parts.

These advantages, the structure, and the operation of the engine of this invention may be understood by considering the following description in conjunction with the drawing in which:

FIG. 1 is a longitudinal sectional view of a fully illustrative portion of a six-cylinder embodiment of the engine of this invention.

FIG. 2 is a cross-sectional view of a portion of the engine of FIG. 1 looking in the direction of the arrows 2 -- 2.

FIG. 3 is a detail view of the piston rod of FIG. 1 looking in the direction of the arrow 3.

FIG. 4 is a chart showing piston travel relative to shaft rotation in the engine of FIG. 1.

Referring now to FIGS. 1 and 2 of the drawing, an internal combustion engine 5 embodying the present invention has a cylinder block 6 which includes six cylinders 7 with their axes parallel and equally spaced on the circumference of a circle, as shown in FIG. 2. At its center, the block 6 has a main bearing 8 which, together with a second main bearing 9, supports a straight and unbroken drive shaft 10 with its axis parallel to the axes of the cylinders 7. The left ends of the cylinders 7 are closed by a head plate 11. Within each cylinder 7 is a piston 12.

A cam drum 13 is mounted on the shaft 10 and locked to it by a key 14. The drum 13 has a larger circumferential wall 13a and a lower wall 13b. The larger wall 13a has a continuous cam face 13c which faces the pistons 12 and causes axial thrusts on the six larger roller cam followers 15, during intervals, as the cam drum 13 rotates. The lower wall 13b has a continuous cam face 13d which faces away from the pistons 12 and causes axial thrusts on the six lower roller cam followers 16, during intervals, as the cam drum 13 rotates. Each set of a follower 15 and a follower 16 rotates on a spindle 17 held in a yoke at the outer end of a piston rod 18 the inner end of which is affixed rigidly to a piston 12. The cam face 13c and the corresponding faces of the rollers 15 are sloped so that their motions will match along the line of contact of the two opposing faces.

A piston rod 18 includes an integral crosshead 19 as shown in FIGS. 2 and 3. The ends 19a of the crossheads 19 travel parallel to the axes of the cylinders 7 in guide and stabilize channels 20a formed in the entire length of each of six support members 20. These members 20 are integral with a base ring 20b conforming with and bolted (not shown) to the end of the cylinder block 6 between its perimeter and the outer sections of the circumferences of the cylinders 7. A circular foot plate 21, which has at its center a main bearing 9, is bolted to the outer ends of the six support members 20. A cover 21a extending between the foot plate 21 and the cylinder block 6 closes the cam case.

Referring again to FIG. 1, an intake port 22 is located so as to be fully open when a piston 12 is at the B.D.C. of the intake stroke. Each piston 12 has a thin apron 12b long enough and wide enough to keep the port 22 closed during compression and exhaust strokes. An exhaust valve 24 is carried by the head plate 11 so mounted that the motion of its stem 24a with head 24b is parallel to the axis of the drive shaft 10. The stem 24a has a guide 24c and a spring 24d. The exhaust cam 25 is at the edge of the cam disk 26 which is fixed to the shaft 10. The cam face 25a bears directly on the stem 24a or an adjusting device (not shown) may intervene.

FIG. 4 shows a graph, "Piston Travel," having piston travel in the engine of this invention as ordinates and degrees of cam rotation as abscissas. A piston 12 performs the four strokes, of one complete cycle in 360.degree., between the head plate 11 of a cylinder 7 and the port 22 fully open position at the B.D.C. of the intake stroke. An exhaust valve 24 is in the head plate 11.

Referring back to FIG. 1, the configuration of the cam face 13c is such that when the cam drum 13 rotates the cam face 13c acting through the follower 15 and the piston rod 18 causes the compression and exhaust strokes of the piston 12 with its face 12a to move inward as shown on the graph. During the power stroke, with the piston face 12a moving outward as shown on the graph, the piston 12 acting through the piston rod 18 and the follower 15 causes rotation of the cam drum 13 by pressure on the cam face 13c. The configuration of the cam face 13d is such that when the cam drum 13 rotates the cam face 13d through the follower 16 and the piston rod 18 causes the intake stroke of the piston 12 with its face 12a to move outward as shown on the graph. The configuration of the cam face 13d causes the piston 12 to be pulled on the power stroke when the charge has not fired as in starting and also prevents over throw near the end of the exhaust stroke.

The interaction between cam faces and followers causes side thrusts. The slope of the line of contact causes an upward thrust and minor thrusts result from the crosshead 19 being in a plane slightly above the level of the side thrusts. All these thrusts are contained by the guide and stabilizing channels 20a which confine all motions other than longitudinal of the ends 19a of the crossheads 19.

Referring again to FIG. 4, the operation during one complete four-stroke cycle, which takes place during one complete revolution of the drive shaft 10, is as follows:

Starting at the beginning of the compression stroke with nearly a full charge in the combustion chamber, the piston 12 is at its B.D.C. with the intake port 22 fully open and the exhaust valve 24 closed.

During the compression stroke, the piston 12 is moved inward by the thrust of the rotating cam face 13c fully closing the intake port 22 after an interval which permits intake of additional charge at higher engine speeds as a result of the inertia of the incoming mixture and moves on to a position which completes compression at a predetermined compression ratio;

During the power stroke, the piston 12 is moved outward by the explosion and expansion of gases to a position just short of opening the intake port 22, its thrust augmenting the rotation of the cam face 13c;

During the exhaust stroke, the piston 12 is moved inward by the thrust of the rotating cam face 13c to a position just short of contact with the head plate 11 thus ridding the cylinder 7 of substantially all waste gases;

During the intake stroke the piston 12 is pulled outward by the thrust of the rotating cam face 13d to the intake port 22 fully open position where it remains stationary until the start of the next compression stroke.

This completes the four strokes of the engine cycle, during one revolution of the drive shaft 10 and the cam faces 13c and 13d.

During the earlier part of the intake stroke, a high vacuum is created within the cylinder 7 because the intake port 22 is not yet exposed and the exhaust valve 24 is closed. When the piston 12 uncovers the intake port 22, this high vacuum causes an inrush of mixture under an initial pressure equivalent to a 100 percent supercharge which soon reduces to the degree of vacuum of the usual intake stroke level. The extended interval, with the intake port 22 fully open, permits the entry of more mixture at high speeds than during the intake interval of a crank drive engine with its intake stroke limited to 25 percent of the four-stroke cycle.

As a result of the high initial intake pressure differential and a longer duration intake stroke, 135.degree. equal to three-eighths of a cycle, this engine will induct, at 50 percent higher speed, the same maximum charge as that of a crank drive engine of the same displacement and thus have 50 percent greater maximum power output. At the same number of cycles per minute at which maximum B.H.P. is attained in a crank drive engine, this engine will have a power output about 20 percent greater.

Referring again to FIG. 1, the exhaust valve 24 is opened and permitted to close by a circumferential cam face 25a of the cam 25 at the perimeter of the cam disk 26 fixed to the shaft 10. This one cam 25 controls the operation of all six exhaust valves 24. The cam face 25a is so shaped as to open the exhaust valves 24 somewhat before the end of the power stroke to accelerate exhaust and to allow them to close only just in time to avoid contact with the piston face 12a.

The basis for the advantages summarized earlier have now been made evident. The embodiment which has been described is a six-cylinder engine. However, any desired number of comparable cylinders, including odd numbers, may be grouped similarly to make a compact engine in each case and with a minimum of parts.

It is now apparent that the invention herein disclosed is well designed to meet the main object of the invention. It is also apparent that the invention is susceptible of refinement, modification, variation, and/or changes without departing from the scope or fair meanings of the claims below.

Claims

What is claimed as new and desired to be secured by letters Patent of the United States is:

1. A multi-cylinder four-stroke cycle internal combustion engine having a cylinder closed at its top, a piston slidable therein, an exhaust valve at the top of said cylinder, an intake port located in the lower portion of the wall of said cylinder, a drive shaft spaced apart from and parallel to the longitudinal axis of said cylinder, cam means circumferencially mounted on said shaft interacting between said shaft and said piston to control the four phases of said four-stroke cycle, a cam surface of said cam means being shaped to provide an intake phase of longer duration than any other phase of said four-stroke cycle, and to provide a substantial interval during the intake phase during which said piston remains at rest at the end of the intake phase while said shaft is rotating, said substantial interval being longer than the interval at the end of any of the other phases of said four-stroke cycle.

2. An internal combustion engine as defined in claim 1 including said cam surface shaped to cause said piston to expose said intake port for an interval during said cycle, said intake port being closed during the remainder of said cycle, and an exhaust valve cam circumferencially mounted on said drive shaft.