US2742032A - Combustion chamber - Google Patents

Description

p i 1956 F. A. WYCZALEK 2,742,032

COMBUSTION CHAMBER Filed Aug. 16, 1952 2 Sheets-Sheet l Inventor gyg y {og/a @czaf Attorneys April 17, 1956 F. A. WYCZALEK 2,742,032

COMBUSTION CHAMBER Filed Aug. 16, 1952 2 Sheets-Sheet 2 Inventor "4 y I I a g5? Attorneys the valves.

United States Patent I COMBUSTION CHAMBER Application August 16, 1952, Serial No. 304,720 11 Claims. or. 123-491) This invention relates to engines and particularly to valve in head, spark ignited, four stroke cycle, internal combustion engines.

It has been proposed heretofore to construct combustion chambers in engines in such a way as to provide a firing chamber communicating with the edge of a minimum mechanical clearance space between the piston and the head of the cylinder. If the valves are placed in the firing chamber then it is difiicult to obtain good volumetric efliciency in the engine because the walls of the firing chamber tend to interfere with the flow of fluid through If the valves are placed in the mechanical clearance space then it is difficult to construct a firing chamber in the head of the engine in which the length of flame travel to different parts of the firing chamber will be equal. If thelength of flame travel to the different parts of the firing chamber is not equal then the places where the flame travel is of greater extent will tend to form pockets where the last parts of the charge may be subject to excessive pressures and temperatures and detonation may result. Instead of locating the firing chamber in the head of the engine it is proposed to project the firing chamber into the walls of the cylinder and the head of the piston.

The spark plug then may be projected through the head in such a way that the gap between the terminals of the spark plug is substantially equidistant from all of the remote walls of the firing chamber. The firing chamber at one edge thereof communicates with the mechanical clearance space between the end of the piston and the head of the cylinder and into which the inlet and exhaust valves of the engine open. The valves are located in the head of the engine in directly opposed relation to the end of the piston and. in such position that the fluid flow through the valves will not be obstructed by any closely adjacent walls forming any part of the combustion chamber. is ignited the greater part of the charge in the firing chamber willburn before the burning is finished in the clearance space. However, the burning of the charge in the firing chamber will terminate substantially at the same time in all of the remote parts of the firing chamber and consequently the tendency for detonation to occur in the firing chamber will be reduced. The high ratio between surface area and volume will tend to reduce the tendency for detonation to occur in the clearance space between the end of the piston and the head of the cylinder.

In the drawings:

Figure 1 is a fragmentary cross sectional view through a cylinder of an engine embracing the principles of the invention.

Figure 2 is a cross sectional view of the engine illustrated by Figure 1. Figure 2 is taken substantially in the plane of line 2-2 on Figure 1 looking in the direction of the arrows thereon.

:Figure 3 is a fragmentary cross sectional view of an engine illustrating another form which the invention may assume. i

When the charge in the combustion chamber Figure 4 is a cross sectional view of the engine disclosed by Figure 3, taken substantially in the plane of line 4-4 on Figure 3 looking in the direction of the arrows thereon.

Referring particularly to Figures 1 and 2, the engine 10 comprises an engine block 11 in which one or more cylinders 12 are formed. The block 11 may be provided with cooling liquid passages '13 which are formed in the walls thereof for cooling the cylinders 12. The upper wall of the block 11 is adapted to be covered by a gasket 14 against which an engine head 16 may be secured by bolts or other suitable fastening means not shown. Each of the cylinders 12 of the engine contains a reciprocating piston 17 having a piston pin 18 by which the piston is pivotally mounted on the end of a connecting rod connected to the crankshaft of the engine. The pistons 17 may be provided with a plurality of piston rings 19 to prevent leakage of fluid between the pistons 17 and the cylinders 12. The head of the engine 16'is formed in such a way as to provide inlet and exhaust passages indicated by the numeral 21. The inlet and exhaust passages terminate in each cylinder in ports 22 which are adapted to be closed by inlet and exhaust valves 23 and 24 for each of the cylinders 12. It is proposed to locate the valves 23 and 24 on a diameter of each of the cylinders 12 and in directly opposed relation to each of the pistons 17. v

In each cylinder 12, the lower wall 26 of the head 16 and the upper wall 27 of the piston 17 are planar in formation and are disposed in closely spaced relation to provide mechanical clearance spaces indicated at 28. In the present instance the mechanical clearance spaces 28 extend in transverse relation to the axes of the cylinders 12, although these spaces may extend at any other angle preferred. The valves 23 and 24 are mounted in the head 16 on sleeve bearings indicated at 29, the latter being rigidly secured in bosses 31 formed in the walls of the inlet and exhaust passages indicated at 21. The head 16 may be cooled by-cooling liquid circulating in passages indicated at 32.

A spark plug such as that indicated at 33 may be employed for each cylinder of the engine 10. The spark plugs may be secured in the lower wall 26 of the head 16 in such a way that the spark gap 34 between the terminals 36 will extend beyond the inner surface of the wall 26. The spark plug 33 for each cylinder is located at one side of and substantially midway between the valves 23 and 24'. The axis .of each of the spark plugs 33 which includes the spark gap 34 is aligned withan element of the cylindrical surface forming each of the cylinders 12. In each cylinder the rings 19 on the pistons 17 are positioned a considerable distance below the ends of the pistons 17 in order to provide room for forming a firing chamber for each cylinder indicated at 37. The firing chamber 37 and the clearance space 28 form a combustion chamber 38 for each cylinder of the engine.

In the structure disclosed by Figures 1 and 2 the firing chamber 37 is formed by walls 39 and 41 extending inwardly at the end of piston 17 above the rings 19 and outwardly of the cylinder 12 and into the jacket space within the block 11. The walls 39 and 41 are spherical segments which, when the piston 17 is at top dead center, form a continuous hemispherical depression; the center of which is at the spark gap 34.

It will be apparent that :the firing chamber 37 has an arcuate edge which=communicates with the mechanical clearance space 28 and that the chamber and the space comprise the combustion chamber 38. The combustion chamber 38 therefore consists of the hemispherically shaped firing chamber 37 and the relatively thin or shallow crescent shaped clearance space 28. The first part of the charge to burn will be in the firing chamber 37 and all parts of the surface of which are substantially equidistant from the spark gap 34 when the piston 17 is at top dead center. Also in the firing chamber 37 the ratio between the surface area and the volume of the firing chamber is numerically small. The last part of the charge to burn is in the clearance space 28, the burning in which commences at the periphery of the firing chamber 37 when the burning in the firing chamber 37 is substantially completed. However, the ratio between the surface area and the volume of the clearance space 28 is numerically much larger than in the firing chamber 37.

In a high compression ratio engine it will be apparent that a considerable part of the charge will be contained within the clearance space 28 and that by reason of the charge burning first in the firing chamber 37 the density of the last part of the charge to burn in the clearance space 28 will be relatively high. However, the tendency of the engine to detonate at such high compression pressures will be opposed by the low surface to volume ratio in the firing chamber and by the higher surface to volume ratio in the clearance space 28. The low density part of the charge in the firing chamber 37 will burn before detonation occurs and the higher density part of the charge in the clearance space 28 will burn at a relatively slower rate. The rate of flame travel in the clearance space 28 will be decreased by two characteristics which are inherent in the design of the combustion chamber. The first of these is that the radiant heat resulting from the burning in the firing chamber 37 will not appreciably affect the temperature of the charge being compressed into the clearance space 28. The second is that the surfaces of the end of the piston and the head will cool the narrow elongated flame as it progresses. across the clearance space 28 from the edge of the firing chamber 37. The flame and charge will be cooled to such an extent that the tendency toward detonation in the clearance space 28 will be greatly decreased.

It will be apparent that the flame travel in all parts of the firing chamber 37 will terminate at substantially the same time and that the flame travel in all corresponding parts of the clearance space 28 also will terminate at substantially the same time. Under such circumstances it will be apparent that there will be no pockets in the combustion chamber where detonation may tend to occur in the last part of the charge to burn in any part of a combustion chamber.

The structure disclosed by Figures 3 and 4 is similar to that disclosed by Figures 1 and 2 and the same reference numerals and description may be applied to the principal parts of the engine. However, the combustion chamber 138 disclosed by Figures 3 and 4 differs in certain respects from the combustion chamber 38 disclosed by Figures 1 and 2. The combustion chamber 138 comprises a firing chamber 137 and a clearance space 128. The firing chamber 137 is semi-cylindrical in form and is disposed at one side of the piston 17 and projects within the piston 17 and across the upper edge of and beyond the cylinder 12. The part of the firing chamber 137 within the piston 17 comprises an axially disposed wall 51, the ends of which terminate in opposed relation to the ends of a cylindrically disposed wall 52 which is formed in the block 11. The lower edges of the walls 51 and 52 when the piston 17 is at upper dead center are joined by a transversely disposed wall 53 formed in both the piston 17 and the block 11. The spark plug 33 is located at one side of the inlet and exhaust valves 23 and 24 respectively but somewhat closer to the inlet and exhaust valves than in the structure disclosed by Figures 1 and 2. In such position the spark plug gap 34 between the terminals 36 of the spark plug 33 is directly above and midway between the ends of the axially disposed wall 51. In order to prevent the end of the piston 17 from hitting the terminals 36 the 4 spark plug 33 is set in a shallow depression 54 in the wall 26 of the head 16 of the engine.

In the structure disclosed by Figures 3 and 4 the burning of the charge will start at the spark gap 34 and will burn simultaneously and in opposite directions within the firing chamber 133 and the clearance space 128. Since the wall 52 is a semi-cylindrical wall formed about the axis of the spark plug 33 it will be apparent that the burning in the firing chamber 138 will be completed practically simultaneously at all parts of the upper end of the semi-cylindrical surface 52. Thereafter the burning will continue downwardly in the firing chamber 138 and likewise will terminate at substantially the same time at all parts of the lower extremity of the semi-cylindrical surface 52. In the clearance space 128 the burning will progress on a narrow arcuate flame front from the spark gap 34- to the opposite extremity of the clearance space 128.

I claim:

1. An engine comprising a cylinder having a reciprocal piston therein and a head closing an end thereof, a pair of inlet and exhaust valves in the head of said cylinder and opposed to the piston in said cylinder, a spark plug in the head of said cylinder and located at one side of said valves, a firing chamber formed in said piston and said cylinder and in directly opposed relation to said spark plug, said firing chamber being formed by an arcuate wall having a center of curvature at the gap between the terminals of said spark plug, and a minimum clearance space formed between the remaining parts of the head of said piston and said cylinder head and communicating with an edge of said firing chamber.

2. An engine comprising a cylinder having a head closing one end thereof and a reciprocal piston therein, a pair of inlet and exhaust valves disposed in the head of said cylinder and directly opposed to the piston therein, a spark plug projecting through said head at one side of and approximately midway between said valves, and a combustion chamber formed between said cylinder, said piston and said head, said combustion chamber being partly formed by an arcuate wall disposed at equal distances radially with respect to the gap between the terminals of said spark plug.

3. An engine comprising a cylinder having a head and a reciprocal piston therein, a pair of inlet and exhaust valves in the head of said cylinder and in opposed relation to the piston in said cylinder, a spark plug in the head of said cylinder and having the spark gap between the terminals thereof substantially aligned with an axially disposed wall of said piston, and a firing chamber formed in said cylinder at one side of said piston and having an arcuate wall the center of curvature of which is at the gap between the terminals of said spark plug.

4. An engine comprising a cylinder having a reciprocal piston therein and having a head closing one end of said cylinder, said head and said piston haivng a pair of parallel walls disposed in closely spaced relation to provide a minimum mechanical clearance space between said head and said piston, a pair of inlet and exhaust valves in said head and opening within said mechanical clearance space, a spark plug disposed in said head at one side of and substantially midway between said valves, and a firing chamber formed in said piston and said cylinder and communicating at one edge thereof with said mechanical clearance space, said firing chamber being partly formed by an arcuate wall formed by parallel and circular surface elements having the centers of curvature thereof on a line extending through the axis of said spark plug.

5. An engine as defined by claim 4 and in which said parallel circular elements forming said wall have centers of curvature intersecting a line along said axis and extending from the gap between the terminals of said spark plug to the opposite side of said firing chamber.

6. An engine comprising a cylinder having a reciprocal piston therein and a head closing an end of said cylinder, a pair of valves in the head of said cylinder and opening into the space between said head and said piston, a spark plug disposed in said head at one side of said valves, and a firing chamber formed in said cylinder and said piston and being formed by walls of said piston and said cylinder having surfaces formed by spherical segments, said spherical segments when said piston is at top dead center providing a continuous wall forming a hemispherical surface having the center thereof at the gap between the terminals of said spark plug.

7. An engine comprising a cylinder having a reciprocal piston therein and a head closing one end of said cylinder, a pair of inlet and exhaust valves in said head in opposed relation to the piston in said cylinder, a spark plug in said head at one side of said valves, the gap between the terminals of said spark plug being disposed substantially in alignment with an element of the surface of said cylinder, and a firing chamber formed in said cylinder and said piston, said firing chamber being formed by walls extending into said cylinder and said piston, said walls when said piston is at top dead center having surfaces forming a continuous hemispherical opening projecting into said piston and said cylinder, with the center of curvature of said surfaces being at the gap between the terminals of said spark plug.

8. An engine comprising a cylinder having a reciprocal piston therein and a head closing an end of said cylinder, a pair of valves in the head of said cylinder and extending into the space between said piston and the head of said cylinder, a spark plug in said head at one side of said valves, and a firing chamber formed in said piston and said cylinder and being formed by walls of said cylinder and said piston, said walls when said piston is at top dead center within said cylinder forming a continuous semicylindrical surface within said piston and said cylinder and with the axis of curvature of the semi-cylindrical surface of said walls being on the axis of said spark plug.

9. An engine comprising a cylinder having a reciprocal piston therein and a head closing one end of said cylinder, a pair of valves in the head of said cylinder and opening into the mechanical clearance space between said head and the end of said piston, a spark plug in said head at one side of said valves, and a firing chamber formed in said cylinder and said piston in opposed relation to said spark plug, said firing chamber when said piston is at top dead center being formed by a semi-cylindrical opening projecting into said cylinder and said piston, said semicylindrical opening being formed by a planar wall formed in said piston in parallel relation to the axis of said cylinder and including the axis of said spark plug and by a semi-cylindrical wall extending into said cylinder and having an axis coincident with the axis of said spark plug.

10. An engine comprising a cylinder having a reciprocal piston therein and a head closing the end of said cylinder, a pair of valves in the head of said cylinder and opening into a space between said head and said piston, a spark plug disposed in said head, a firing chamber formed within adjacent walls of said cylinder and said head and said piston, said adjacent walls having surfaces formed by spherical segments providing a hemispherical surface having the center thereof at the gap between the terminals of said spark plug when said piston is at top dead center position in said cylinder.

11. An engine comprising a cylinder having a reciprocal piston therein and a head closing the end of said cylinder, a pair of valves in the head of said cylinder and opening into the space between said head and said piston, a spark plug disposed in said head and between said valves, a firing chamber formed within adjacent walls of said cylinder and said head and said piston, said adjacent walls having surfaces formed by spherical segments providing a hemispherical surface having the center thereof at the gap between the terminals of said spark plug when said piston is at top dead center position in said cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 1,781,039 Treiber Nov. 11, 1930 2,012,895 Sidney Aug. 27, 1935 FOREIGN PATENTS 177,409 Great Britain Mar. 30, 1922 101,721 Sweden June 3, 1941

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