US2316794A - Combustion chamber - Google Patents

Description

April 20, 1943.

' G. T. JOHNSON COMBUSTION CHAMBER Filed July 24, 1941 2 Sheets-Sheet l INVENTOR 650 295 TJOHNSON I I I ATTORNEY April 20, 1943.

G. T. JOHNSON COMBUSTION CHAMBER Filed July 24, 1941 47 7 ll I t;

4 43, I l 42- I /V 2 Sheets-Sheet '2 INVENTOR GEORGE 7. JoH/vsou ATTORNEY Patented Apr. 20, 1943 2,316,794 I V v COMBUSTION CHAMBER George T. Johnson, Denver, Colo. Application July 24, 1941, Serial No. 403,791

4 Claims.

This invention relates to internal combustion engines of the compression ignition, fuel injection type, and more particularly to the combustion chambers of such engines.

It is a principal object of this invention to provide controlled turbulence with respect to time and degree that will conform to the requirements of combustion in its various phases.

More specifically, it is an object of the invention to transfer most of the air through separate passages to a restricted combustion zone, and nullify the establishment of high turbulence there n by causing the separated vair portions to flow in opposition to each other.

A further object is to impart moderate and directed movement to the air during the fuel injection period to facilitate fuel mixture and distribution.

Another object is to produce a new and improved method of displacing the compressed air charge and releasing the combustible mixture so as to reduce heat losses and to facilitate combustion.

Other objects relate to: uniflow scavenging of the residual products in the combustion chamber; the imparting of turbulence during the latter part of the combustion process; novel and simple structural components and arrangement of same for embodying the invention; and otherwise to impart improved engine performance.

These and any other objects of the invention which may become apparent as the description proceeds are achieved by means described in the following specification, and illustrated in the accompanying drawings, in which:

Figure 1 is a transverse section through the upper portion of an engine, taken on a plane through the cylinder axis, as represented by line l -i, in Figure 2;

Figure 2 1s a plan section showing the pertinent elements on broken planes perpendicular to the cylinder axis, as represented by the line 2-2, in Figure 1:

Figure 3 is a plan section, similar to that shown in Figure 2, perpendicular to the cylinder axis, as represented by the line 3-3, Figure 1;

Figure 4 is a view showing the parts that form the combustion chamber, in side elevation, looking from the inside of the cylinder toward the ports in the wall of the combustion chamber, the parts of the cylinder block and cylinder head which enclose the combustion chamber being shown in section taken on line 4-4, Figure 1;

Figure 5 is a fragmentary, top plan view of the cylinder liner;

' isometric views the middle Figure 6 is an elevation of the upper portion of the cylinder liner, partially in section, and as projected directly from the plan view of Figure 5;

Figures 7 and 8 show respectively in enlarged member of the three piece combustion chamber assembly in spaced apart relation with the cylinder liner; Figure 9 is a transverse, fragmentary section similar to that of Figure 1 and showing a modifled arrangement of the combustion chamber assembly.

Referring more particularly to the drawings, a cylinder block is indicated at I 0, and secured thereupon is a cylinder head H. The cylinder bloclg is preferably bored to receive a cylinder liner i2, the upper part of which is provided wtih a shoulder l3 to seat in a registering counter bore I4 in the top portion of the cylinder block. The inner cylindrical wall ii of the cylinder liner provides the guiding surface for the reciprocating piston i6, which is of usual construction with a preferably fiat head H. The normally lower surface I8 of the cylinder head extending trans- 31581)! over the cylinder bore is also preferably The cylinder head is provided with the usual air inlet passage and exhaust passage (not shown) leading to respective inlet and exhaust ports 20 and 2l'opening into the cylinder bore. Anair inlet valve 22 is associated with the port 20 and derives its opening motion from an engine driven mechanism including a rocker arm 23 and a push rod 24. The rocker arm is pivoted in a bracket 25 which is mounted on the cylinder head. The valve is normally maintained closed by the usual compression springs 26. An exhaust valve and actuating mechanism therefore (not shown) is in s r manner associated with the port 2 I. Suitable passages 21in the cylinder block and 28 in the cylinder head are provided for the circulation of a cooling medium.

The engine illustrated is of the multicylinder, four-stroke cycle type and operates on compression ignition, whereby air charges drawn into the cylinders are compressed, and during said compression liquid fuel in atomized form is injected into and mixed with the air to form a combustible mixture which ignites under the influence of heat derived from further compression. The admission of air into the cylinders and the expulsion of the products of combustion therefrom are provided for in accordance with customary practice by means of the poppet type valves and associated mechanism as shown on the drawings.

Movement of the pistons is translated into rotary motion through the usual connecting rod and crank shaft linkage (not shown).

Pertinent to the present invention the engine further includes a combustion chamber preferably of spherical form in which the air and fuel charges are diffused and ignited, and which is in two-way communicationwith the cylinder.

The combustion chamber is indicated generally at 29, laterally and above the cylinder bore and in close proximity chamber comprises an assembly of three parts; the external lateral surfaces of which are cylindrical, and formed about a common axis to the same diameter. The circular end surfaces of the three parts are on parallel planes atright angles to their common longitudinal axis.

The combustion chamber assembly is included within both the cylinder block and the cylinder head, which are respectively bored in registering relationship for accommodating the assembly as indicated at 30 and 3|. The bore 3| in cylinder head is completely enclosed by the surrounding walls 32 adjacent the cooling passage, but the bore 30 in the cylinder block intersects the counterbore |4 provided for the cylinder liner l2, and is therefore joined thereto on the chordal plane common to both bores. The axis of the bores 30 and 3| is substantially parallel to the axis of the cylinder and lies in the transverse center plane passing therethrough.

The upper end of the cylinder liner I2 is cut away on its external surface to form a flat surface 33 parallel to the axis of the liner, and a shoulder 34, as shown in Figures 5 and 6. The

thereto. The combustion I middle the width of the notch 40 in the cylinder liner, thereby permitting the intermediate portion between the recesses to fit into the notch 40 and close the upper portion thereof. The recesses 43 accommodate the top portions of the cylinder liner adjacent the notch 40, and each recess comprises three surfaces at right angles to each other whicdcorrespond with co-matingmale surfaces of the cylinder liner as clearly shown in Figures 7 and 8.

The a 'embled alignment -of the lower and embers, together withthe cylinder liner thus provides a continuous passageway 44 affording communication laterally from the walls of the *working'cylinder to the combustion chambe! tangentially thereof.

The port 45 in the inner wall of the cylinder liner leading to the passageway 44, is alternately I covered and uncovered by piston l6. 7

The outer wall 46 of the middle member 42 intermediate the recesses 43 is of concave curvature corresponding in radius to the inner wall the movement of the of the cylinder liner, and in the assembly is coninder liner.

surface 33 is on the chordal plane of intersection between the counter bore l4 and the bore 30, and the shoulder 34 is in the transverse plane defined by the bottom of the bore 30.

The lower member 35 of the combustion chamber assembly is bottomed in the bore 30 I and overlaps the shoulder 34 of the cylinder liner l2. A cylindrical segment is cut away from the member 35, leaving a fiat surface 36 which is on the chordal plane of intersection between the bores l4 and 30. In assembled relationship the surface 33 of the cylinder liner and the surface 35 of the lower member of the combustion chamber assembly are in close-fitting engagement.

Perpendicular to the surface 36, and centrally thereof, is formed a n tch 31 which is open to centrictherewith.

A notch 41 is formed in the middle member 42. intersecting its upper face and the outer wall portion 46'of concave curvature. The lower surface of the notch 41 is inclined upwardly away from the cylinder, and is so contoured that its line of intersection with the concave surface 49 lies in the transverse plane of the top of the cyl- The lower surface of the notch 41 intersects the upper face 42 in a line spaced from, but closely adjacent to,

the combustion chamber.

The combustion chamber portions embodied within the lower and middle members constitute substantially the lower hemispherical part of the combustion chamber. The remaining upper hemispherical part is embodied within the upper member 48. A notch 49 is formed in the nor,- mally lower surface of the upper member 43.

i The normally upper surface of the notch 49 is the normally upper of the lower member,

and extends therethrough to the portion of the combustion chamber 29 included therein. The side faces 38 of the notch 31 are preferably vertical, and the bottom surface 39 is formed transversely to the radius of the combustion chamber. and tangentially thereto.

The upper end of the cylinder liner has a notch 40 formed radially through the flat surface 33 and centrally thereof, and to a depth correspond ing in assembled alignment to the bottom surface 39 of the notch 31 in the lower member 35 of the combustion chamber assembly. The bottom surface 4| of the notch 40 conforms in contour to the bottom surface 39 of the notch the two notches have the same width.

The middle member 42 of the combustion chamber assembly rests on the lower member 35 in axial alignment. therewith, and covers the notch 31. Recessed segmental portions 43 are formed in the lower face and outer wall of the middle member 42 to each side of the transverse center line of the cylinder. The two recesses 43 31, and

upwardly inclined with respect to the cylinder axis, and opens into the combustion chamber tangentially thereof, and is transversely contoured to the same curvature as the combustion chamber. A notch 50 in alignment with notch 49 is formed in the lower face of the cylinder head II, and intersects the bore 3| therein.

The inclination of the upper 49 and 59 is preferably somewhat less-with respect to the inclination of the lower surface of notch'41, thereby providing a passageway 5| of progressively diminishing area in the direction of the combustion chamber. The upper tangential passageway 5| constituted by notches 41, 49 and 50 is preferably of the same width as the lower tangential passageway 44, and in vertical alignmenttherewith. The intersection 'of the notch 50 with the lower face of the cylinder head forms the port of the upper tangential passageway 5| opening into the working cylinder, and

said port overlies the working cylinder at the periphery thereof. The lower two members of the combustion chamber assembly are fixed in alignment by abutment against the flat surface 33 of the cylinder liner. The upper member is fixed in alignment with the lower two members by the dowel pin 52.

A fuel injection valve 53, preferably of the single orifice, pinile type, V inder head ii and projects therethrough, and

through the lateral wall remote from the cylinder of the middle member surfaces of notches is mounted in the cylis nearing the end or its stroke, and therefore of the upper member 48 of the combustion chamber assembly through suitable apertures. The injection valve is positioned radially of the combustion chamber, and its longitudinal axis lies in the common transverse vertical plane of the working cylinder and the combustion chamber, and intersects the interior wall nearest the cylinder of the middle member 42 substantially midway between the two tangential passages.

The combustion chamber 29 as formed within the three piece assembly has been shown as offset with respect to the outer cylindrical wa'1ls\ of the assembly, thereby providing walls of heavier section on the side toward the cylinder where the tangential passages occur. This construction permits of the novel arrangement of parts as between the three piece assembly and the cylinder liner as heretofore described.

In the operation of the engine, including the present improvements, air is admitted to the cylinder through the intake port during the suction stroke of the piston, and is compressed during the succeeding return stroke. As the compression pressure increases, the air within the working cylinder is displaced into the preferably spherical combustion chamber 29. Up to the point where the piston covers the port 45, leading to the lower tangential passageway 44, the air has access to the combustion chamber through both passageways 44 and SI. Each passageway as heretofore described is tangential to the combustion chamber, and air displaced thereinto through either passage would normally swirl rapidly in accordance with the direction of entry. As shown by the arrows in Figure 1, the air portions introduced simultaneously through the lower and upper passages are respectively in opposition to each other. Thus, the condition prevailing within the combustion chamber prior to the closing of the port 45 by the piston is characterized by a relatively non-turbulent or rules cent state due to the dampened energy of the opposing air streams.

Mechanical clearance only is provided between the head I! of the piston and the under face of the cylinder head at the T. D. C. position. After the port 44 has been closed and during the remainder of the piston stroke, the volume of air yet to be displaced enters the combustion chamher through the top passage only and swirls counterclockwise as shown in Figure l. The positive unidirectional swirl thereby produced during the latter portion of the compression stroke is of only moderate intensity; sufiicient for the function of aiding fuel and air mixture, without having the objectionable tendency to extinguish the initial flame nucleus; an attribute ,common to engines employing high velocity swirl in the combustion chamber.

Fuel is normally timed for delivery to the in- Jection valve 53 by the fuel pump (not shown) somewhat in advance of the T. D. C. position, which occurs during the period that air is being displaced into the combustion chamber through only the upper passage; in other words, after the port 45 has been closed by the piston, and the air becomes moderately activated in the combustion chamber.

The fuel charge enters the combustion chamber from the far side thereof with respect to the cylinder, and the fuel spray is directed across the air stream preferably in the range between the two passages. The movement of the air stream is not of high velocity owing to the fact that the piston which causes the displacement moving at relatively low velocityv The combustion-chamber is always open to the cylinder through the passage overlapping the cylinder bore, and following the reversal of the I piston on its power stroke the burning mixture expands into the cylinder first through the overlapping passage, and subsequently through both said passage and the piston controlled passage. The movement of the gases through the piston controlled passage into the cylinder is characterized by a unifiow condition due to the gases taking oil tangentially from the previously established counter-clockwise rotation within the combustion chamber. This, together with the fact that two passages thorough scavenging of the combustion chamber. The uniflow exit ofthe gases through the piston controlled passage is necessarily somewhat retarded and the delayed introduction into the cyl-.

inder sustains turbulence during the later stages of combustion, contributing thereby to the efficiency of thecycle.

The two passages converge toward the cylinder, and the gas streams issuing simultaneously from th passages intersect in a common zone, and said action contributes to the dispersion and propagation of the burning mixture within the cylinder.

Heat losses are lessened through the walls of the combustion chamber, owing to the average low intensity of turbulence maintained therein.

In Figure 9 showing a modified construction. the mating end surfaces of the lower and middle members of the combustion chamber assembly comprise conical instead to provide a tapering section to the piston controlled passage. With this construction a somewhat larger volume of displacement occurs through the passage overlapping the cylinder re. While I have shown and described specific embodiments of my invention, it is not intended that protection shall be limited thereto, but only by the scope of the appended claims.

Having described the invention what is claimed as new is:

1; In an internal combustion engine of the fuel injection, compression-ignition type having a cylinder block provided with a cylinder bore, a cylinder head having an inner face extending across one end of the bore, and a piston slidably mounted in the bore, the walls of the cylinder block and the cylinder head having a spherical combustion chamber closely adjacent and at the side of the cylinder bore, the top of.v the combustion chamber bein above the lower surface of the cylinder head, and walls forming an upwardly and outwardly extending passageway communicating between the cylinder bore and the spherical combustion chamber, above the upper limit of piston travel, the cylinder wall having another passageway communicating the interior of the combustion chamber with the cylinder bore at a point below the top of the piston travel, the two passageways opening tangentially into the combustion chamber and converging towards the center of the cylinder bore.

2. In an internal combustion engine of the fuel injection, compression-ignition type, having a cylinder block provided with a cylinder bore in which a piston is mounted for reciprocation, the wall of the cylinder bore having a. combustion chamber of substantially circular cross section positioned to one side of the bore adjacent the up per limit of piston travel, the wall of the 002m are available makes for more of fiat surfaces in order bustion chamber having two outwardly converging passageways communicating the interior of the combustion chamber with the cylinder bore, one of the passageways opening into the bore above the upper limit of piston travelwhereby it is always open,

during the compression stroke, a combustion supporting medium is tlrstadmitted to the combustion chamber through two vertically spaced openings and finally through the upper opening only and whereby during a portion of the power stroke gases from the combustion chamber are delivered to the cylinder in two convergent streams. r

3. In an internal combustion engine of the fuel injection, compression-ignition type having a cylinder block provided with a cylinder bore, a cylinder'head extending across and closing one end of the bore, and walls iorming a spherical combustion chamber at one side of the cylinder bore, two outwardly convergent passageways extending and communicating between the combustion chamber and two vertically spaced points in the cylindrical bore, the upper of which is above the upper limit 0! piston travel and the lower being so positioned that it is wholly covered the other'passageway opening into the bore at a point below the upper limit of piston ,travel whereby it is covered by the piston as it approaches its upper limit of travel, and whereby :bore, the top of the by the piston when it is in its uppermost position, and means tor injecting a spray of combustion chamber, the spray being directed to that portion of the wall of the combustion chamber that is positioned between the passazeways.

4. In an internal combustion engine of the fuel injection compression ignition type having a cylinder blockprovided with a cylinder bore, a cylinder head having an inner face extending across one end of the bore, and a piston slidably mounted in thebore, the walls oithe cylinder block and the cylinder head having a combustion chamber of substantially circular cross section a closely adjacent and at the side of the cylinder l GEORGE 'r. JOHNSON.

fuel into the combustion chamber being above the lower surface of the cylinder head, and V 7 Walls forming an upwardly'and outwardly ear-- the cylinder bore. V

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