US2792817A - Internal combustion engine - Google Patents

Description

y 21, 957 w. H. SMITH 2,792,817

INTERNAL COMBUSTION ENGINE Filed Nov. 29, 1955 INVENTOR.

ATTORNEY m in United States Patent'O INTERNAL COMBUSTION ENGINE Warren H. Smith, Detroit, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application November 29, 1955, Serial No. 549,745

5 Claims. (Cl. 123-65) This invention relates to an internal combustion engine and more particularly to such an engine adapted to burn a gaseous fuel.

Among the principal objects of the invention is to provide such an engine with means including an improved combustion chamber adapted to improve the firing regularity in the individual engine cylinders, reduce the general noise characteristics of the engine, improve thefuel economy of the engine, and permit the use of higher compression ratios.

The combined means for accomplishing the foregoing and other objects and advantages of the invention will be more thoroughly understood from the following description of a preferred embodiment thereof in which reference is made to the attached drawing, in which:

Figure 1 is a longitudinal sectional view of an engine cylinder embodying the invention; and

Figure 2 is a sectional view of the head portion of the engine cylinder taken substantially on the line 2-2 of Figure 1.

Referring more particularly to the drawing, Figure 1 shows a cylinder assembly for a loop-scavenged, twocycle, internal combustion gas engine. The cylinder assembly includes a cylinder block having a sleeve-lined bore 12 therein reciprocably mounting a piston 14. The bore 12 is closed at its upper end by a cylinder head 16 which may be formed integrally of the block, as shown, or may be several of the block and suitably secured thereto. Intermediate its ends, the cylinder block and the cylinder liner are provided with a plurality of aligned air inlet passages 18 and ports 20, respectively," and with a plurality of aligned exhaust passages 22 and ports 24, respectively. As is conventional in such two-cycle, loopscavenged engines, the inlet and exhaust ports are controllatble by the piston and subtend arcs on opposite sides of the cylinder. The exhaust ports 22 .are' of greater longitudinal dimension that the inlet ports 20 and, consequently, are opened earlier by the downward movement of the piston and are closed laterby the upward movement of the piston than the inlet ports. The inlet passages 18, the ports 20, and the crown of the piston are formed so as to cause the scavenging and charging inlet air to travel upwardly adjacent the inlet side of the cylinder toward the cylinder head and across the cylinder head thereby forcing the exhaust gases downwardly on the exhaust side of the cylinder and out through the exhaust ports as indicated by the arrows a in Figure 1. As the inlet ports and subsequently the exhaust ports are closed by the upward compression stroke of the piston, the movement of air thus initiated in the cylinder when the ports are open results in a clockwise vortical circulation of the entrapped air charge within the cylinder as viewed in Figure 1.

As the piston 14 approaches its uppermost position as shown in Figure 2, the crown of the piston and the coacting surfaces of the cylinder head 16 define a combustion chamber 26 therebetween. In the illustrative em- 2,792,817 Patented May 21, 1957 bodiment of the invention, the opposed surfaces of the head and piston crown'include coacting frusto-conical outer surface portions 28 and 30, respectively. The piston crown is also provided with a central bowl 32 of the open or semi-turbulent type while the central portion of the cylinder'head is substantially flat except for a semi-discal groove 34 opening on said chamber and extending transversely thereof from the inlet side to the outlet side of the cylinder. A gaseous fuel inlet passage 36 in the cylinder head terminates in a port 38 opening on the groove 34 adjacent the inlet side of the cylinder, and a poppet valve 40" associated with the port 38 is adapted to control the sequential admission of fuel into the cylinder. While two spark plug's'42are shown mounted in the head, the spark-gapjends of which project into the groove 34, in transversely spaced relation to the poppet valve, any suitable ignition-initiating device such as a pilot fuel oilinjector or glow plug'might besubstituted therefor, and it is not essential to the practice of the invention that more than one ignition device be utilized.

In high-compression gas engines of this type, it is essential that the air charge supplied to the individual cylinders be in excess of that required to support the complete com-bustion of the gaseous charge and that the ignition timing or firing regularity within the several cylinders is properly controlled so that the power generated by the combustion .of the gaseous charge is smoothly applied to the piston'and consequentially to the associated parts of the engine. However, if the required excessive air charge were completely mixed with the gaseous charge, a relatively lean power or noncombustible mixture would result. Hence, it is necessary that the gaseous charge within such engine cylinders be presented to the ignition device in a relatively rich mixture, with subsequent mixing of the gaseous and air charges occurring as a result of the initial combustion process.

In the embodiment of the invention herein described, as the piston 14 approaches its uppermost position, a portion of the vortically circulating air charge is enrapped between the coacting frusto-conical surface portions of the head and piston crown and, consequentially, is forced r-adially inwardly of the combustion chamber. This inward movement of this portion of the air charge tends to set up toroidal air flow between the cylinder head and the bowl of the piston crown as indicated by the arrows b in Figure 2. However, this toroidal air flow is broken into two semi-toroids disposed on opposite sides of the piston by a trough of air which continues to circulate vortically within the groove 34 and a diametrical portion of the piston bowl as indicated by the arrows c. At a predetermined point in the operating cycle for the particular engine cylinder, generally as the piston approaches its uppermost position, the poppet valve 40 is caused to open admitting a gaseous fuel charge into the cylinder. In accordance with the invention, the vortical flow of the air charge confined within the groove 34 and the aforementioned diametrical portion of the piston bowl carries a stratum of relatively rich combustible mixture from the port 38 to the zone where the igniting device is effective to initiate combustion. Since the velocities of the vortically circulating air will be a function of the speed of the engine, a definite time relationship relative to the operative position of the piston can be established between the opening of the valve 40 and the time that the combustible mixture reaches the effective zone of the igniting device. Consequently, firing within each cylinder may be carefully regulated to achieve a relatively smooth propagation of the combustion flame front as the remaining gaseous charge is mixed with the remaining air charge by the turbulence induced by the initial combustion. In this manner, the combustion-generated power is applied 3 relatively smoothly to thepi'stons and associated parts of the engine thereby increasing the operative life of "such parts and reducing the noise level of the engine.

It will thus be seen that the several objects and advantageous results of the invention are achieved in the illustrative embodiment of the invention. While only one preferred embodiment of the invention has been shown and described, it will be appreciated by .those skilled in the art that various modifications maybe made therein without departing from the spirit and scope of the invention as defined in the following claims.

I claim:

1. In an internal combustion engine, a cylinder having a head closing one end, a piston reciprocably mounted in said cylinder, said head and said piston defining a combustion chamber therebetween, means associated with said cylinder for introducing .an air charge therein .and for inducing a vortical circulation of the air charge causing the air to move toward said head adjacent one .side of the cylinder and away from said head adjacent the diametrically opposite side of the cylinder, said head having a groove therein opening on and extending diametrically of said cylinder from said one side to said opposite side, means for sequentially introducing gaseous fuel into said groove adjacent said one side, and means transversely spaced of said last-mentionedmeans within said groove for initiating combustion of a combustible mixture of said fuel and said air carried thereto by the vortical flow of said air.

2. In an internal combustion engine, means defining an expansible combustion chamber including a cylinder element closed at one end and a piston element mounted therein, said cylinder element :and 'said piston element being reciprocable relative to each other, means associated with atleast one of said elements for introducing an air charge into said expansible chamber and for inducing vortical flow of said air .charge therein, a groove in at least one of said elements opening on said combustion chamber and extending in the direction of 'said'vortical flow, means for introducing a gaseous fuel into said groove, and ignition-initiating means :in said groove spaced from said fuel-inducing means whereby a stratum of combustible mixture of said fuel and said air is carried to said ignition-initiating means by the vortical flow of air within the expansible chamber.

3. In a two-cycle gas engine, the combination including a cylinder having a head closing one end thereof, a piston reciprocably mounte'din said cylinder, the opposed surface portions of said piston and said hea'ddefining a combustion chamber therebetween, saidhea'd having a semidiscal groove opening on said combustion chamberrand extending transversely of said cylinder, valve means for introducing gaseous 'fuel into one end of said groove, an ignition-initiating device spaced transversely of said cylinder from said'valve means within said groove, said cylinder having a plurality of air inlet and exhaust ports intermediate its ends controllable by the piston, said ports and said'piston being formed to 'eausethe 'scavenging'and charging inlet air to travel upwardly in a column adjacent said one side of the cylinder toward said head thereby inducing a vortical flow of the charging air within the cylinder, said vortical flow being adapted to carry a stratum of relatively rich combustible mixture of said fuel and said air from said valve means to said ignition-inducing device Within said groove.

4. In a loop-scavenged, two-cycleigas engine, the'combination including a cylinder having a'headlclosing one end thereof, a piston reciproca-bly mounted insaid cylinder, said cylinder having a plurality of air inlet and exhaust ports intermediate its ends and controllable by said piston, said ports and said piston'being formed so as to cause the scavenging and charging inlet air to travel upwardly in a column adjacent one side of the cylinder toward said head thereby inducing vortical flow of the charging air within the cylinder, the opposed surface portions of said piston and said closed end defining a combustion chamber therebetween including coating frustoconical outer surface portions, said piston having a bowl therein centrally of the frusto-conical outer surface portion, said head haw'ng a semi-discal groove opening on said combustion chamber and extending transversely of said cylinder, valve means for introducing gaseous fuel into one end of said groove and an ignition-initiating deviced spaced transversely of said cylinder from said valve means within said groove, the outer surface portions of said piston and said closed end forcing air entrapped therebetween during the compression stroke of said piston into said central chamber with a toroidal motion, and said vortical flow being adapted to carry a stratum of relatively rich combustible mixture of said fuel and said air from said valve means to said ignition-inducing device within said groove.

5. In an engine, means defining an expansible combustion chamber including a cylinder element .closed at one end and a piston element mounted therein, said cylinder element and said piston element being reciprocable relative to each other, a groove in at least one of said elements opening on said combustion chamber, means for introducing a gaseous fuel into said groove, ignitioninitiating means in saidgroove spaced from said fuel-inducting means, and means associated with at least one of said elements for introducing an air charge into said expansible chamber and inducing vortical .flow within said chamber whereby a stratum of combustible mixture of said .fuel and said air is carried directly from said fuelintroducing means tosaid ignition-initiating means within said groove.

References Cited in the file :of this :patent UNITED STATES PATENTS 2,391,176 .Mallory Dec. 18, 1945

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