Synthesis Procedure and Combustion Chamber With Variable Turbulence

This application is a national phase application corresponding to PCT/RO81/00002 filed Apr. 21, 1981 and based, in turn, on a Romanian national application 100981 filed Apr. 27, 1980.

This invention refers to a procedure and a combustion chamber with variable turbulence for use in high speed engines and to a method of operating same.

In the Ricardo procedure and combustion chamber, high speed operation is effected using a divided chamber, with swirl organized circulation, the connection section between the pre-combustion chamber and the main chamber being constant during the whole cycle and of an optimized value of one percent of the active surface of the piston. On the other hand, the process and the combustion chamber have the disadvantage that during the fuel passage in both directions through the choke section high gasodynamic losses arise and cause relatively high specific fuel consumption and do not assure a complete organization of the fluid circulation in the divided chamber, the central and peripherical areas being left unorganized.

A unitary combustion chamber and its operating process are known in which the absence of chokes in the fuel path assures a relatively low fuel consumption, but this system has the disadvantage that high speed operation is not possible because of a reduced level of the swirl organization.

According to the present invention, these procedure and synthesis combustion chamber eliminate the above disadvantages are obviated in order to achieve a low fuel consumption and to increase the flexibility of the engines with compression ignition, both for the speed range and/or the load range, and for the size range, by assuring an integral volumetric organization of the fluid circulation in the combustion chamber. This is achieved by dividing only temporarily the space of the swirl chamber from the combustion chamber located above the piston, only during the compression period, for the rest of the cycle the combustion chamber forming a unitary whole with the swirl chamber, the combustion process in its aggregate constituting a synthesis between the combustion precesses of the unitary and divided chambers, the intensification of the swirl being obtained as a result of the vectorial summation of at least three swirls, with tridimensional circulation and the revaluation of the threshold effect created by the piston, which points out the effect of the fluid passage between the two enclosures of the combustion chamber which are separated by a space profile that penetrates in the separating channel. This profile is defined by at least three directing surfaces, which generate swirls with tridimensional circulation and which constitute the mobile braking threshold of the swirling enclosure, concerning the rich burning mixture in the passage. The fluid circulation in the swirl enclosure is determined so that it should meet the fuel jet in the equiflow and displace a part of the fuel onto the incandescent head of a spark plug.

In the drawing:

FIG. 1 is an axial section through a combustion chamber formed at the free end of a piston of an engine according to the invention;

FIG. 2 is a plan view of a portion of this end of the piston;

FIG. 3 is a section taken along the line I--I of FIG. 1;

FIG. 4 is another plan view of the piston profile;

FIG. 5 is a section through an engine according to the invention in the region of the combustion chamber;

FIG. 6 is a view similar to FIG. 5 but illustrating a second embodiment; and

FIG. 7 is a further section through an engine representing a third embodiment of the invention.

The combustion synthesis procedure, according to the present invention, consists in the separation of the turbulence chamber space from the combustion chamber compartment located above the piston, only during the injection, mixture making and combustion periods, namely during the final compression phase, during the rest of the cycle the combustion chamber being unitary. Thus, a reduction of the gasodynamic losses as well as a complete organization of the circulation, as a consequence of the vectorial summation of at least three swirls with tridimensional circulation are assured.

According to the present invention, the combustion procedure leads to the intensification of the turbulence by turning to good account the threshold effect which emphasizes the passage effect. The highest levels of the two effects are situated at different angles in the evolution of the cycle, the passage effect appearing the first.

According to the invention, the combustion chamber is made up of an enclosure a, which represents the divided space situated in a cylinder head 11 and an enclosure b, situated in a piston 2, which represents the second space of the combustion chamber. The two combustion spaces a and b, are linked by a groove c, formed between an inner surface d of a refractory insert 3 and an adequate profile e, forming one piece with piston 2. The groove c has a variable section only at the end of the compression phase on a period of approximately .+-.15.degree.-20.degree. RA round the bottom dead center. The maximum section of the groove c is established in such a way that the withdrawal of the piston 2 unifies the spaces a and b, and creates an approximately unitary chamber.

The spatial profile e on the piston 2 is defined by two slope angles, namely f.degree. and g.degree., which also represent the main direction of organizing the circulation of fluid between enclosure a and enclosure b.

The two angles f.degree. and g.degree. ensure the formation of some swirls h, respectively of some symmetrical-toroidal swirls i, which totalize vectorially and generate a tridimensional circulation completely organized in the whole volume of the combustion chamber. Ensuring a completely organized circulation in the whole volume of the chamber, we may use some injectors 4 with one or more injection ports whose jets are correlated with air circulation through the combustion chamber.

The possibility of using multi-port injectors permits the application of the invention, to the large size engines too.

The synthesis combustion chamber formed by the enclosure a temporarily divided and the enclosure b may be achieved in different embodiments, both as far as the form of enclosure a and the form of enclosure b are concerned, as well as the partition ratio between these enclosures.

In a first embodiment, represented in FIG. 5, the divided space a has a spherical-conical form and the partitioning degree is about 50% and the air circulation in the final phase of compression, in the first place comes upon an incandescent spark plug and then penetrates in the injection area, drawing the fuel flow in the equiflow.

In the second embodiment, according to FIG. 6, the swirl enclosure a has a cylindrical-spherical form, which permits a better integration of the fuel flow in the organized fluid and in the position ratio which is closer to 100%. The air circulation in the final compression phase, in the first place comes upon an incandescent spark plug 5 and then penetrates in the injection area, drawing the fuel flow in the equiflow.

In a third embodiment, represented in FIG. 7, the fluid flow goes across enclosure a of the combustion chamber, coming upon the fuel flow, which is drawn in the equiflow and part of the flow is deposited on the incandescent top of spark plug 5. In this manner a reduction of delay at self-ignition is achieved, thus reducing the toughness of Diesel engines and facilitating the meeting of multi-fuel combustion conditions.