GB2067242A

GB2067242A - Mixture preparation for pre- combustion chamber i.c. engines

Info

Publication number: GB2067242A
Application number: GB8000867A
Authority: GB
Original assignee: Ustav Pro Vyzkum Motorovych Vozidel
Current assignee: Ustav Pro Vyzkum Motorovych Vozidel
Priority date: 1980-01-10
Filing date: 1980-01-10
Publication date: 1981-07-22
Also published as: GB2067242B

Abstract

Apertures 13 in the tube 11a provide for passage of rich mixture, produced in the tube in the main passage 5 by the fuel injector 10, to a chamber 12 communicating with the pre-combustion chamber intake passage 8. The chamber 12 may have a controllable air inlet passage (18), Figs 2 and 3 (not shown). A single injector 10 may be located upstream of the respective main and pre- combustion chamber intake passages 5 and 8 of a multi-cylinder engine, Fig. 4 (not shown). <IMAGE>

Description

SPECIFICATION Method of preparation of a combustible mixture for engines with divided combustion space and arrangement for execution of this method The invention relates to combustion engines with reciprocating or rotating movement of pistons with a divided combustion space and particularly to a method of preparation of a combustible mixture for these engines and to an arrangement for execution of this method.

Engines with a divided combustion space, where in addition to a main combustion space a subsidiary combustion space, connected therewith is provided, are known. A main suction channel controlled by a main suction valve terminates into the main combustion space, from which a discharge channel, controlled by a discharge valve is branching. A subsidiary suction channel controlled by a subsidiary suction valve terminates into the subsidiary combustion chamber, which is connected with the main combustion chamber by a flash-over channel. A spark plug or some other ignition means of the combustible mixture is situated in the subsidiary combustion chamber.

A poor combustible mixture is supplied to the main combustion chamber and an easily ignitable combustible mixture to the subsidiary combustion chamber. The spark plug ignites the combustible mixture in the subsidiary combustion chamber in a position of the piston in the neighbourhood of the upper dead end of the compression stroke. The hot gases flash-over from the subsidiary combustion chamber over a flash-over channel into the main combustion chamber and are igniting the poor combustible mixture therein. It is also known that for a correct operation of the described method two combustible mixtures with different mixing ratio have to be provided, a poor mixture for the main combustion chamber and a rich one for the subsidiary combustion chamber.Known designs of similar engines use for preparation of both kinds of combustible mixtures two separate devices, either two separate carburettors, the control of which is accomplished for instance according to the USA patent specifications No. 1 ,568.638; 2,121.920; 3,092.088; 3,230.939; 3,880.942 or according to German patent specifications No. 2,259.286 and others or by a combination of a carburettor and an injection device, known for instance from engines Honda and Volkswagen (Registered Trade Marks). A drawback of these known arrangements is both the requirement following from the design of the use of two either same or different devices and their dependent control requiring substantially complicated mechanical or other devices.

It is an object of this invention to provide a method of preparation of a combustible mixture of different mixing ratio and an arrangement for execution of this method, which would be simple, reliable, would enable a simple control of the mixing ratio of both kinds of combustible mixtures and which would eliminate drawbacks of known arrangements.

The method of preparation of a combustible mixture with different mixing ratio for the main and subsidiary combustion chamber for engines with a divided combustion space has been according to this invention solved in that the combustible mixtures for both combustion chambers are formed from a single fuel jet, injected into the main air stream sucked on into the main combustion chamber, whereby a part of the fuel is separated from the fuel jet by a subsidiary air stream, sucked-on to the subsidiary chamber.

The combustible mixture for the subsidiary combustion chamber is furthermore according to this invention adjusted by a supply of additional air which is advantageously taken from the main stream of sucked-on air.

The subsidiary stream of sucked-on air can be furthermore taken from the main stream of sucked-on air.

For execution of the method according to this invention an arrangement has been proposed, where part of the fuel is sucked-on to the subsidiary chamber and is furthermore adjusted by supply of additional air.

A stub nipple encompassing the fuel jet is open into the main suction channel, to the main suction conduit or to the mixing chamber of suction conduits.

It is advantageous to connect the sucking-off chamber with the main suction conduit by a channel for additional air or to connect it both with the main suction channel and with the main suction conduit by an annular passage around said stub nipple. The channel for additional air can be connected with the main suction conduit by an opening, into which a conical end of a regulating screw is engaging, or it can be connected by an air chamber with the suction tract of the engine, whereby the throttling cone of the regulator of additional air engages into the air chamber.

An air chamber for additional air can be provided in the channel for additional air.

A throttling flap may be provided in the main suction conduit in direction of passage of the main sucked-on air in front of the collecting conduit of the main suction conduit.

A throttling flap can be furthermore provided in the main suction conduit in direction of passage of the main sucked-on air in front of the mixing chamber.

The solution according to this invention provides for an engine with divided combustion space the advantage of a perfectly prepared combustible mixture with two mixing ratios using a single injection device of any system, for instance with low, medium or high pressure, with continuous or intermittent ejection.

The main advantage of this solution over known arrangements is mainly the more perfect maintenance of the same mixing ratio of the combustible mixture and its distribution to individual cylinders, enabling to achieve for an equal mixing ratio of the combustible mixture lower values of the content of harmful substances in the waste gases, particularly of nitrogen oxide and the possibility to achieve a higher specific output with a simple design without requirement of extraordinary and costly solutions of the combustion system.

The invention will be described and explained in more detail on examplary embodiments on hand of attached drawings, where Fig. 1 is a sectional elevation of an arrangement according to this invention provided on a single cylinder of an engine, Fig. 2 a partial sectional elevation of the suction system of the engine with the supply of additional air, Fig. 3 a diagrammatic sectional elevation of an adjustable air chamber for additional air, Fig. 4 a sectional elevation of an arrangement of the suction system with fuel injection into a single place of the suction conduit of a multicylinder engine, Figs. 5, 6 and 7 are diagrammatic sectional elevations of alternatives of the design of the sucking-off chamber according to this invention with an injection nozzle.

Fig. 1 shows the fundamental arrangement according to this invention provided on a single or multicylinder ignition engine comprising a cylinder head 1 where a main combustion chamber 2 is provided, closed by the face wall 3 of the piston, possibly also by the wall of the engine cylinder. A main suction channel 5 controlled by a main suction valve 4 terminates into the combustion chamber 2. A subsidiary combustion chamber 6 is connected with the main combustion chamber 2 by means of a flash-over channel, into which subsidiary combustion chamber 6 a subsidiary suction channel 8 controlled by a subsidiary suction valve 7 is terminating. A spark plug 9 is provided in the subsidiary combustion chamber 6.

A main suction conduit 17 terminating into a collecting conduit 14 is connected with the main suction channel 5, to which collecting conduit 14 a body with a throttling flap 15, a regulator 16 of the amount of fuel and further parts of the suction system of the engine are connected. A holder 11 of a fuel injection nozzle 10, provided with a stub nipple 11 a determines in the cylinder head 1 the sucking-off chamber 12, connected with the main suction channel 5 by openings 1 3 arranged in the stub nipple 11 a. The sucking-off chamber 12 is connected by a subsidiary suction channel 8 with the subsidiary combustion chamber 6.

Fig. 2 shows an arrangement, where a channel 1 8 for additional air terminating for instance into the collecting conduit 14, is connected to the subsidiary suction channel 8. The air chamber 1 9 for additional air can be either a single one for all engine cylinders or be separate for each cylinder.

The channel 1 8 for additional air enables the adjustment of the mixing ratio of the combustible mixture for the subsidiary combustion chamber 6 and together with openings 13 its amount.

Fig. 3 shows an examplary embodiment of a regulator 27 of additional air arranged in the channel 1 8 for additional air, the throughflow section of which is controlled in dependence on the operating conditions of the engine. A control device 20 actuates for instance in dependence on the engine load the throttling cone 21 and changes thus the throughflow cross section of the air chamber 28 for additional air. An opening provided in the wall of the suction conduit, controlled by a regulating screw 23 serves for fine adjustment of the amount of additional air.

Fig. 4 shows an arrangement of a multicylinder engine, where the fuel injection into the suction conduit 1 7 is accomplished by a single fuel injection nozzle 10 for all engine cylinders.

The fuel injection nozzle 10 arranged in the holder 11 injects fuel into the mixing chamber 24 of a common suction conduit, wherefrom the combustible mixture is distributed to individual engine cylinders by respective branches of the suction conduit 1 7. The holder 11 forms by means of the stub nipple 11 a in its seating a sucking-off chamber 12 which is connected both by openings 13 with the suction conduit 1 7 and by the channel 18 for additional air with the subsidiary suction channel 8. The rich mixture for the subsidiary combustion chamber 6 s taken by this arrangement from a single place. A possible adjustment of the mixing ratio can be equally accomplished by a single device.

Fig. 5 shows an example of a design of the holder 11 with the stub nipple 11 a with the fuel nozzle 10 and the situation of the holder 11 in the suction conduit 1 7 for creation of a sucking-off chamber 12. The fuel injection nozzle 10 terminates into the internal space of the stub nipple 11 a.

Close to the mouth of the fuel injection nozzle 10 openings 13 are provided, by means of which the sucking-off chamber 12 is connected with the suction conduit 1 7. The sucking-off chamber 12 is also connected with the subsidiary suction channel 8. A channel 1 8 for additional air enabling without great difficulties the adjustment of the mixing ratio of the combustible mixture according to requirements of operation of the engine is arranged in parallel or in series with the suckingoff chamber 12. The mixing ratio of the combustible mixture for the subsidiary combustion chamber 12 can be adjusted by additional air also with regard to operating conditions of the engine Fig. 6 shows an alternative solution according to this invention by pressing-in the holder 11 into a bore of a neck of the cylinder head 1 of the engine cylinder or of the suction conduit 17.

Additional air passes via an annular passage 26 between the external wall of the stub nipple 1 la and the bore of this neck.

Fig. 7 shows a similar solution as in Fig. 6 with the difference, that additional air is supplied to the sucking-off chamber 12 over the channel 18 for additional air, terminating in an inclined direction into the suction chamber 1 7.

The arrangement according to this invention operates as follows: An amount of fuel which together with the sucked-on amount of air forms a mixture of the required overall mixing ratio is supplied via the fuel injection nozzle 10. Due to thermodynamic changes in the ejected fuel jet its most easily evaporating components are released in the neighbourhood of the mouth of the fuel injection nozzle 10 which components together with the best atomized fuel are due to the stream generated in the stub nipple 11 a by the injected fuel jet and by sucking-off by the subsidiary suction channel 8 taken along into the subsidiary combustion chamber 6. This combustible mixture has a minimum tendency to condense on the walls of the subsidiary suction channel 8.As for suckingon of a fresh fuel dosis of the combustible mixture into the engine the same limit conditions are prevailing as in the main and subsidiary suction channel, the ratios of sucked-on amounts of combustible mixtures into both combustion chambers 2, 6 depend on hydrodynamic properties of both systems. These can be chosen so that the ratio of both amounts of combustible mixtures is decreasing with increasing load of the engine or is increasing. It has been observed that the degree of distribution of combustible mixtures, expressed by the ratio of fuel supplied into the combustible mixture into the subsidiary combustion chamber 6 to the amount of fuel in the combustible mixture supplied into the main combustion chamber 2 depends only littie on the revolutions of the engine.The mixing ratio of the combustible mixture in the subsidiary combustion chamber 6 can be controlled within a wide range by the size of the stub nipple 11 a, by the diameter of openings 13 or by the size of supply conduits, or by the auxiliary air which is taken along, according to need from the suction system between the stub nipple 11 a and the cleaner of sucked-on air and introduced into the subsidiary suction channel 8.

The selection of these values depends on the used injection device. In case of any change of the ratio and amount of the combustible mixture for the subsidiary combustion chamber 6 the overall mixing ratio of the combustible mixture remains a function of the fundamental adjustment of the injection device.

In order to secure a good operation of the arrangement it is from the point of view of preparation of the combustible mixture advantageous to use for a more perfect atomization of the fuel jet the subsidiary air supplied from the space in front of the throttling flap 1 5 to the mouth of the injection nozzle 10, particularly for the subsidiary combustion chamber 6 at low engine load and when using low pressure injection devices. The amount of air depends on the magnitude of underpressure in the suction conduit 1 7 behind the throttling valve 1 5 and on the magnitude of the cross section at the place of its outlet near the fuel nozzles 1 0. As the pressure difference in the outlet cross section of air is critical from a certain engine load on, the atomizing of fuel by this method is rather efficient.

The intensity of evaporation and the stability of the combustible mixture sucked-off into the subsidiary combustion chamber 6 depends on the atomizing of fuel. In a limit case the amount of air can achieve the amount required for idle run.

Claims

1. Method of preparation of a combustible mixture with different mixing ratio for a main combustion chamber and a subsidiary combustion chamber of engines with divided combustion space, where the combustible mixture for both combustion chambers is formed from a single fuel jet, injected into the main air stream sucked-on into the main combustion chamber, whereby a part of the fuel is separated from the fuel jet by a subsidiary air stream, sucked-on into the subsidiary combustion chamber.

2. Method as claimed in claim 1, where part of the fuel sucked-on into the subsidiary combustion chamber is furthermore adjusted by supply of additional air.

3. Method as claimed in claim 2 where the additional air is taken from the main stream of sucked-on air.

4. Method as claimed in claim 1, where the subsidiary stream of sucked-on air is taken from the main stream of sucked-on air.

5. Arrangement for execution of the method as claimed in claim 1 comprising a combustion engine with a main combustion chamber with a main suction channel and a subsidiary combustion chamber with a subsidiary suction channel, a suction valve provided both in the main and in the subsidiary suction channel, the main suction channel forming part of the suction tract of the engine, a fuel nozzle generating a fuel jet terminating into the suction tract of the engine, a stub nipple encompassing the outlet of said fuel nozzle while remaining open into the suction tract of the engine, a sucking-off chamber provided around said stub nipple, openings formed in said stub nipple near the outlet of the fuel injection nozzle connecting the internal space of the stub nipple with the sucking-off chamber, the subsidiary suction channel connecting this sucking-off chamber with the subsidiary combustion chamber of the same cylinder, means for igniting the combustible mixture in the subsidiary chamber, a flash-over channel connecting the subsidiary combustion chamber with the main combustion chamber.

5. Arrangement for execution of the method as claimed in claim 1 comprising a combustion engine with a main combustion chamber with a main suction channel and a subsidiary combustion chamber with a subsidiary suction channel, a suction valve provided both in the main and in the subsidiary suction channel, the main suction channel forming part of the suction tract of the engine, a fuel nozzle generating a fuel jet terminating into the suction tract of the engine, a stub nipple encompassing the outlet of said fuel nozzle while remianing open into the suction tract of the engine, a sucking-off chamber provided around said stub nipple, openings formed in said stub nipple near the outlet of the fuel injection nozzle connecting the internal space of the stub nipple with the sucking-off chamber, the subsidiary suction channel connecting this sucking-off chamber with the subsidiary combustion chamber, means for igniting the combustible mixture in the subsidiary chamber, a flash-over channel connecting the subsidiary combustion chamber with the main combustion chamber.

6. Arrangement as claimed in claim 5, where the stub nipple of the fuel injection nozzle terminates into the main suction channel.

7. Arrangement as claimed in claim 5, where the stub nipple of the fuel injection nozzle terminates into a suction conduit which is part of the suction tract of the engine.

8. Arrangement as claimed in claim 5, comprising a mixing chamber for the suction conduits, the stub nipple terminating into this mixing chamber.

9. Arrangement as claimed in claim 5, comprising a channel for additional air, connecting the sucking-off chamber with the main suction conduit.

10. Arrangement as claimed in claim 5, comprising an annular passage around the stub nipple of the fuel injection nozzle, said annular passage connecting the sucking-off chamber both with the main suction channel and with the main suction conduit.

11. Arrangement as claimed in claim 5, comprising a channel for additional air, provided with an opening, a conical end of a regulating screw engaging into this opening, said opening connecting said channel for additional air with the main suction conduit.

12. Arrangement as claimed in claim 5, comprising a channel for additional air, an air chamber, a regulator of additional air, a throttling cone engaging into the air chamber, the channel for additional air connected with said air chamber.

13. Arrangement as claimed in claim 5, comprising a channel for additional air, with an air chamber in said channel.

14. Arrangement as claimed in claim 5, comprising a main suction conduit and a collecting conduit of suction conduits, throttling means being provided in the main suction conduit in direction of passage of the main sucked-on air in front of the collecting conduit of suction conduits.

1 5. Arrangement as claimed in claim 14, a throttiing flap forming said throttling means.

1

6. Arrangement as claimed in claim 5, comprising a mixing chamber as part of the suction tract of the engine, a main suction conduit connected to this mixing chamber, a throttling flap provided in said main suction conduit in front of said mixing chamber.

17. Method of preparation of a combustible mixture with different mixing ratio for a main combustion chamber and a subsidiary combustion chamber of engines with divided combustion space, substantially as described.

1 8. Arrangement for preparation of a combustible mixture with different mixing ratio for a main combustion chamber and a subsidiary combustion chamber of engines with divided combustion space, substantially as described, with reference to the attached drawings.

New claims or amendments to claims filed on 26/3/81 Superseded claims 1 and 5 New or amended claims:

1. Method of preparation of a combustible mixture with different mixing ratio for a main combustion chamber and a subsidiary combustion chamber of engines with divided combustion space, where the combustible mixture for both combustion chambers of the same cylinder is formed from a single fuel jet, injected into the main air stream sucked-on into the main combustion chamber, whereby a part of the fuel is separated from the fuel jet by a subsidiary air stream, sucked-on into the subsidiary combustion chamber.